It's funny coz John is genuinely an abusive father but "'toxic' masculinity" has nothing to do with it.
John did not want Dean to be more masculine. He specifically wanted Dean to parent Sam. Be his caretaker, his cook, his teacher, his brother, his emotional support. AND his protector. Which means he must now shape up and be a good fucking hunter because if he fails, Sam could die!
(Nm that Dean can also die. John simply sidesteps this. I don't think he wants Dean to die. But he wants to sidestep that possibility by saying: if you're a good enough hunter, you shouldn't be fucking dying).
Those are not masculine traits John is emphasising at all. Even if you claim hunting is masculine (and there's no proof John did), the rest of the parentification Dean faced is also abuse and that's "feminine". So what, he wants both? Except that's not how literally anything works, so please don't let the villains of the show fool you into thinking like this lol. "Hunting is macho" - only ever said by villains. The main characters all welcome more people being aware of how to fight the supernatural threats. Women included. They don't care.
And I really do think John would expect theee exact same things if Dean was a girl. This is genuinely not a gendered activity. This is about his paranoia and refusal to take accountability for himself and his role as a father. John happens to be right about supernatural threats even, but importantly, he doesn't know that. He let his fear, anger, and grief overshadow his actual responsibilities.
If Dean were a girl, it would make him more vulnerable in the eyes of the outside world, maybe. Maybe. But the realities and abilities that go into hunting, caretaking, parentification, etc. all remain the same. John may be more strict in his training of her, if he's sexistly inclined to believe girls aren't as naturally good at hunting. But we know John has met and befriended very skilled female hunters. The gender is not the issue to him. What he expects from a mere child, thing he himself cannot give, those things that emptied Dean out completely - those are the things that make John so abusive.
If we must speak on gender and sexuality and pressures, I'm more inclined to believe that John picks up on the fact that Dean is definitely queer in some way, and he clocks the fact that it makes him more vulnerable. And that's why he's such an ass. He liked Lee, remember. (And I bet he would initially continue to like Gordon even after knowing Dean is hooking up with him lol). He's not an idiot. He's just a deadbeat. He knows Dean is so open with his heart literally all the time, and I bet it scares the shit out of him. He doesn't know how to make Dean more armoured. So he just keeps telling him to be more ruthless, more obedient, and more of a weapon. All the while putting him down verbally. So that he can make Dean the scapegoat AND delegate the duty of protecting Sam to Dean entirely. In his mind, Dean can't afford to be dilly dallying. Esp when anyone could be a demon and whatnot. Focus. Protect Sammy. And I'll go off and find the demon who killed mom.
And he definitely respects Sam as a child and an individual in a way that he doesn't for Dean. Which is not to say he's good to Sam, or that he respects Sam as a whole. Just that his abuse of Sam was entirely different. Sam was sheltered in comparison to Dean (means nothing much lol), and he was also kept out of reach of knowledge. The same things that traumatised John, John did to Sam. He doesn't respect Sam for the act of being rebellious imo. What he respects is the fact that Sam and John can be a lot alike at that point in time. He likes the fact that they both get so fucking angry BUT they'll unite just like that. A few key reassurances, and they're on the same side again. John gets Sam a bit more. He's so mad when Sam leaves for Stanford. In that moment, I don't think he respected it at all. But later, Sam and John can both laugh about it. Sam is not going to hold John to account quite as much.
With Dean, I bet he's suppressing a lot of guilt (and this is part of why he keeps transferring that to Dean). Dean was not kept out of the loop. John can't lie to Dean. He can't pretend their differences have been dealt with. Dean Knows. And knows with too much clarity for his comfort. And Dean will always forgive John, maybe. But he won't agree to a quick revisionism. Not without Knowing. (Like the Sonny lie). So he just keeps deflecting random negative shit to Dean to keep him reeling and then moves on. He can't really stay still with Dean unless it's for his own purposes (ahem John death speech).
And none of this is because John is sexist. He's extremely fucked up, yes. But we don't actually have evidence in canon that he was super sexist.
