"Jotaro Kujo is Weak at His Core"
As a writer and avid character psycho-analyzer, I find this concept fascinating because I wholeheartedly agree with what OP has quoted from a "What opinion would get the community to do this? *Insert Johnny getting torn apart*" post.
Before I begin, I know some people will see this, misread it, and immediately say "lmao did we watch the same show? He's strong, badass, and can kick anyone's ass. Like do you know Star Platinum bro?". Trust me, I've seen the replies to this post and they said this same exact thing.
And I'm here to say that to said people, if you truly are not the illiterates I'd like to term you as, you'd take the time to realize that when we say "he's weak", we're not referring to his physical prowess because we know he's one of the strongest characters in the show.
If you don't like to, then you're just proving the accuracy of the last sentence: "You can't stand seeing your edgy badass image of Jotaro as vulnerable."
Pushing that aside, I'd like to expand on OP's opinion/headcanon with some depth to it and explain how exactly he's "weak" outside of being a skilled and strategic fighter.
I've learned that to be holistically healthy, one needs to develop and maintain all optimal functions of oneself: Physical, Emotional, Social, and Mental.
Obviously, Jotaro excels in the physical category. He's conventionally attractive, taller than the average male population, well-defined with a muscled build, fit as hell, street and book smart, and highly in tune with his environment making him adaptable in any circumstance.
He's "strong" in that aspect we all know at a superficial level.
However, we start to see the core problem once we strip this good-hearted man of his physical appeal:
Emotional? He believes he doesn't need to express them to others because why should he. He refuses to process them and instead keeps them behind a locked wall of stoicism and aloofness.
Social? Can't communicate to save his life. He's reclusive and doesn't know how to socialize outside of work. Guarded and skeptical around others. Too much of a workaholic to bother making new acquaintances (if he even knows how) outside of familial connections.
Mental? At 17, he went on a death crusade over Asia and the Middle East, almost died numerous times, and most likely lived with unresolved PTSD that carried over into adulthood, and further deteriorated his already poor social and emotional skills.
What do we have then? If we look past that powerful exterior of a man, we have inappropriate emotional expression, poor socialization, and constant fatigue of dealing with bullshit that relates to his trauma.
And this is what we mean by his "core": His mindset. His inner machinations. The soft spot his enemies would need to target in order to defeat or kill him, strategy-wise.
I. Emotional
We pretty much already know how this man handles emotions. And this may come off as "irrelevant" to the dudebros and the meme riders who believe "haha feelings are for pussies, I advocate for edgy autistic Florida man who don't give a fuck, elopes with dolphins, and berates women".
But believe it or not, he has them, just like any other human being on the planet. I said it once and I'll say it again: Not everyone will wear their heart on their sleeves. Some will convey emotions publicly with no issue, while others would prefer to keep to themselves.
But how does this contribute to him being "weak" at his core?
Essentially, it's similar to how someone with depression may behave (not everyone, some of them). One may appear friendly, sunny, and bubbly to everyone around them, not knowing they're actually suffering from a void that eats them up from the inside when alone.
For his case, it may look like he doesn't care about what happens to him and everyone around him, considering his nonchalant and aloof behavior, but beneath that cold exterior, he cares way too much for his family, friends, and allies. He feels too much to the point where once his allies are endangered, he would sacrifice his well-being without a second thought.
And that's an issue to him.
To him, emotions make him vulnerable and in his circumstance where enemies are actively hunting him down trying to find his weak spots, his emotions should be kept behind doors because he doesn't know how to regulate it on the outside so it's either total stoicism or lashing out.
I found someone saying this line about him that fits him so well: "He's a good person who doesn't know how to be a good person."
This is a man who means well and truly wants to help out of the goodness of his heart, but because of his inability to convey his emotions properly and is unable to pick up emotional cues, it can lead to shit tons of misunderstandings due to inappropriate tone & expression, and that can change how someone views him in the long run, thus leading to unintended deterioration of personal relationships (which contribute to the social aspect of his weakness).
I found a visual representation of what I just said above. Just to give context: The show is about a married couple who struggles to keep their relationship afloat, having to navigate through family politics, work & life balance, and miscommunications so they could find why they loved each other in the first place.
The emotionally-reserved character here with the poor communication skills is the girl. She's a CEO who just received a call, came out from work, and meets with her husband, asking him to accompany her to a doctor's appointment.
Observe how she thinks she views herself VS how others actually view her as.
Other's POV: Demanding, brash, and insensitive Her POV: Anxious, hesitant, and confused
Now remember what Araki had written about Jotaro? "He doesn't believe he must reveal his emotions to others because he thinks everyone can figure him out, leading him to be a victim of misunderstandings. Others think him to be cold-hearted, rebellious, and insensitive."
II. Social
With emotions as our base foundation to poor communication skills, this leads us to his weak socialization aspect.
In a recent quote reblog about how he was raised as a child may have contributed to his tough persona, I mentioned something about his need of "Security".
Growing up, it was mostly just him and his sweet pacifist mother Holly. Joseph couldn't have visited often (he hates Japan) and his dad is a busy musician with a packed schedule on tour. As a kid up to early adolescence, he was coddled by his mother and raised as a good student. Everything was going great for him.
[In popular headcanon] Once he passed puberty, the change to his Part 3 MC era began. People began picking fights with him and bullying him, and he began to see the world as a threat to his safety. Knowing his mother, he wouldn't rely on her to defend him against these dangers. She was too kind, too friendly, too loving for her to deal with the harsh life he now has to deal with.
So he had to be the stronger one for both of them. He already had the physical attributes for it, so why not use it to his advantage?
He got on the popular delinquent trend back in 80's Japan, integrated a couple of cool masculine-esque personalities as his own from his favorite Western and Crime media, and is then able to project this menacing aura everyone should be afraid of, to ward potential threats away from him and his mother.
But Mijin, how does this make him weak? What does this have to do with his need for security?
Think about it: The poor guy's already introverted, doesn't feel comfortable with his emotions that he can't express properly, and now he has to be skeptical with people around him because he realized how shitty society can be, which leads to intimidation that wards off not only potential foes but potential friends as well, making it look like he's anti-social.
On the outside, people are likely to think that he likes being this way when in reality, he seeks a reliable support system on which he can lean onto. Everyone with a sound mind wants that subconsciously because we are social creatures. It's part of our nature.
He's constantly fearful of his surroundings, growing even more vigilant as he ages, but he doesn't look afraid because he chooses to put on a brave face to challenge said fears instead of acknowledging he's scared. I read somewhere in an ask that's not mine that in the manga, some panels actually depict Jotaro shaking/trembling in a mix of fear and adrenaline during some of his fights.
He wants to be around people who he can trust. People who he can lower his defenses with. People who are capable of protecting him just as he is capable of protecting them. People who can face his intimidating aura and challenge it to stand on equal grounds with him or to remind him of his place when he goes too far with certain things. Hence, why he seems comfortable being with the Crusaders.
For once, he wants to feel safe.
To not feel like he has to be this strong pillar of hope that everyone depends on.
To be someone being protected, instead of the other way around where he was always the strong protector. He wants a life of normalcy where he can just be a marine biologist and a professor with a loving family he can come home to.
But that can't happen. The inner circle of friends he counted on is either dead or far away, leaving him even more fearful of the world around him. This results in even more guarded skepticism, always watchful of who's an enemy Stand user and what their Stand could do. Because of his cautious nature, this leads to minimized socialization with others.
With little to no solid support system he can count on, he has no one he feels completely secure with because he believes danger will always come to hurt and/or kill those near him. He doesn't want to burden others with the issues & responsibilities of dealing with Stand users. He wants them to live the normal life he could no longer have.
He doesn't trust in the capabilities of his loved ones when it comes to defending themselves against the amount of potential threats and dangers he has faced, and yet he cares about them dearly. So, he commits to what seems to be the most practical solution in his mind: Self-Isolation.
To be a distant beacon where danger is attracted to and away from those dear to him.
(As we see in the beginning of Part 3 where he willingly locks himself in jail as soon as he sees himself as the threat, and in Part 6 where he stays away from his family once he realizes his enemies were targeting him).
"Your family is your weakness."
All this leads him to become what Araki always envisioned him to be: A lone hero.
III. Mental
Now onto the last part, this part of the essay will focus more on the popular headcanon the community has made about him: "Jotaro has PTSD."
Considering what he's been through at only 17, it would be no surprise that he'd acquired major trauma after those 50 days. Think about it- he gets injured more times than he can count, almost dies numerous times, sees his grandfather get "killed" in front of him, and all this combined with the constant reminder that his mother's life is also on a time limit. A failure to kill DIO meant a failure to save Holly.
The amount of pressure and risk he had to endure for her (and there will still be people who adamantly believe that he hated Holly because he said "bitch" to her twice in the first two episodes).
Now, remember when I said about him having this mentality of over-independence when dealing with stressors? It was still manageable during Stardust Crusaders, but because of what had transpired in Cairo, that mindset carries on to the rest of his adulthood, more so if we consider that he most likely didn't get any therapy or treatment for his trauma.
It might be normal for a teenager to hold onto this stubborn notion of "I can do this by myself" and be casual about it, but with trauma now involved, that notion warps into a persisting belief of "by doing this myself, no one else will get hurt" (i.e. refusing help, doing solo fieldwork, self-isolation).
But Mijin, you keep saying "mentality" this, "mindset" that. What are you talking about?
There's an old Tumblr post I found that talks specifically about this in great detail, but to put it shortly: Jotaro has always wanted to do things by himself because he believes that not only will the task be done with, there would be no one else involved with it, making it better for him to cope mentally if ever shit hits the fan (tying back to poor emotional expression and insecurity in bonds).
If any injuries were to be inflicted, he would be the one to receive them, and he alone, because who knows how he'll react and/or cope when his allies are harmed instead of him over and over again? (refer to the trauma of Jotaro surviving Cairo while the majority of the team that went with him died a.k.a "survivor's guilt")
(Also, refer to how he had exhibited great distress when Jolyne was about to be struck by a rain of knives that Pucci sent)
This might also be the reason why he's more self-sacrificial as an adult: Will be the bait during the rat episode instead of Josuke, takes the brunt of Sheer Heart Attack's explosion to spare Koichi, dives straight onto a path of bullets to save Jolyne, etc.
The only possible solution so he could snap out of that belief he holds on to is that strong, reliable support system he internally needs. People who can help him without sustaining fatal injuries in the process [social]. People who he can approach to release any pent-up frustrations and inner conflicts [emotional].
If he had found those people, then he might have been able to deal and/or cope with his trauma better instead of letting it linger and change his outlook in life [mental].
But we all know how his life went in canon. One moment he's a kid playing ball with his mother, then in his last, he dies by having his head bisected by a time-altering Stand.
Jotaro is a person with a gold heart and a rough exterior. Someone who wants to help and protect his loved ones from the unpredictability of the world the best that he can. But even then, his best wasn't enough. His fear was masked with an air of strength and capability, perhaps as compensation for everything else he lacked:
Adequate processing of emotions.
Stable connection with familial, platonic, and romantic bonds.
A sound mindset that stems from effective coping for his PTSD.
We could only hope in headcanon land that he had a better chance at life in the Ireneverse where he finally could develop his inner core better and get that long-deserved break he had always wanted.
