I completely agree with the cult analysis, but I think there's one thing which hasn't been said about why girls, in particular, are so attracted in their early teens. And that's basically the patriarchy, in particular the relentless sexualisation of teenage girls.
Up until puberty, we tell girls that they can do anything, and be who they want. Then they get to thirteen, develop breasts and they discover that they can't, that boys and men are going to see them as sexual objects and not listen to what they say. It's reductive, grim and at that age pretty terrifying. How do you opt out of this? Well, you could cut your breasts off and say you are a man...
I've seen so many threads about trans daughters on here where the unifying factor is that the daughter had unusually large breasts and so couldn't escape the prison of men's objectification.
And it's not anything new either - but up until now anorexia was the most dramatic / effective solution for the teenage girl, to starve those breasts off and get rid of the objectification. Or less problematically - and I am showing my age her - to be a goth or an emo, to opt out of being conventionally 'attractive' and so of being judged.
But thanks to online porn, the sexualisation is both more relentless, is more graphic from their own peers and so is more frightening.
Trans is the newest and most socially acceptable - in all sorts of ways - means of opting out, and finding a safe space where you don't have to be part of the system.
There's loads more to work through in this - I suspect that one additional reason why transition is very appealing to people with ASD is not just a way of sorting their difference and finding a place to belong, I suspect that they find the mating rituals of teenagers hard to fathom and would quite like an alternative.