I do understand not reading smut, or not reading smut about a specific ship, full stop. I do get that.
What I don't really get are the mind acrobatics who go "Well, if this character were x years older then I could read/write about them having sex!!". I don't get it, but if it helps you sleep at night, you do you.
But what just completely escapes me are the people who then, additionally, come into smut set in canon and clutch their pearls pretending like you are the weirdo here for... looking at the source material as is, seeing the chemistry between the characters and going "Yeah, they should fuck nasty". Who make their own moral dilemma everybody else's problem.
Even though that one is so much weirder than people who write based on canon because, big news: You still thought about that teenaged character fucking!! In fact, you thought about it much harder than the person who just wrote about the sex, because you needed to additionally make up a new scenario that would "justify" that teenaged character having sex! You needed that teenaged character to have sex so badly, you had to age them up just so you could write/read about them having sex!
The person who just writes smut set in the canon timeline knows there is nothing wrong with teenagers having sex. Real life teenagers have sex all the time. But these are not real life teenagers, these are teenaged fictional characters. Heck, chances are the very character this is about had sex in canon. Because it is really, really normal for teenaged characters to have sex, not just in fanfiction, but in the source material too.
But the person who thinks there is something wrong with teenaged characters having sex, and they still thought real hard about that teenaged character having sex and had to make up their own fake scenario to justify why they are making that canonically teenaged character have sex? When you don't have to ship teenaged characters, when you don't have to read/write about them having sex if that goes against your own personal morals? But you still chose to do that? Even though you think it's wrong? You went out of your way to make up reasons to do it?
Now that? That is weird. And you truly have no leg to stand on pretending that the people who are normal about their fiction are weird or creepy. You're at the devil's sacrament too, just because you tell yourself you're there because Lucifer used to be an angel before the fall doesn't change anything.