In my personal experience, the problem with masking is that it's extremely tiresome and I don't care that much about what random asshole urbanites may think of me since there's no possibility of recipocrity if later on they want to genocide me because I looked at them wrong or because I walk too fast for their likeningI pretty much entirely agree with you, though I don't think the comparison with /r/aspergers or /r/egg_irl is quite fair. I do think about it constantly and ask myself whether I am at risk of falling down the confirmation bias hole.
I also think that it's important to always remember that it is only meaningful to describe someone as having ASD if there's a plethora of coincidental different features. There is no sense in suggesting ASD, if all the signs are all down a single axis, e.g. not having friends, a girlfriend and being a virgin are all similar and highly correlated independent of any autism. Something like that can be just as labelled as 'socially awkward/inept' or something like. Slapping the autism label on it doesn't offer any real explanation or practical benefit and as @Crunchy Leaf points out, it can be actively harmful.
The Ayla/'Alan' girl is interesting in part because she has a whole set of orthogonal signs including sensory issues (clothing as a child, aversion to touch), social issues (highly introverted*, anxiety), identity issues (uncertain sense of self, highly conscious sense of wearing a mask, trooning out) and sexual issues (sex aversion, uncertainty over what 'sexual attraction' is, inability to discern targets of sexual attraction). It's the combination of signs that makes autism seem likely.
Additionally, she impresses me as someone who would actually benefit from having the label since she is actively looking for explanation regarding her feelings and sexuality which means there is probably some very real practical benefit. Especially, if it helps her get out of troondom (even if she shouldn't think of it like that, or of autism as a totalizing replacement for 'gender dysphoria' for that matter).
*There was a post I didn't screencap which she subsequently deleted in which she elaborated on how she'd always been markedly introverted.
I think a key point that probably does get lost when people talk about 'masking' in autism and the likes is that it isn't just a case of having different selves or even imitating others. But, rather it's about intellectualizing or rehearsing it heavily alongside not understanding - at least instinctively - why you should do something. Furthermore, there is a common view that you'll hear about how it means people "can't tell" or something, but that's not true. You can tell, it's just that it's a bit like troons and passing; you look at a 'Zeke' and think "this fella looks bit odd," but absent the requisite knowledge you don't necessarily end up adding the "because she's female." It's the same with "masking" in autistic girls, they give away signs like being unusually stereotyped or rigid in their mannerisms or speech. For example, they learn that you should react a certain way when people tell them good news and then they react in exactly that way to all good news. This will come off as being odd or maybe insincere, but again you don't think 'autism.'
If you forget this caveat, then 'masking' just becomes an excuse to exempt yourself from ever having to display any particular behavioral pattern. This renders your supposed autism entirely subjective and impervious to criticism.
It can be an issue even amongst more reponsible activists or clinicians, where they can get too caught up with the problem of underdiagnosis that they destroy all diagnostic rigor. It's probably unavoidable, you can't help but assume that what was good for you must be good everyone.Of course, that's precisely what's going to happen on reddit/tumblr etc.. You can then combine that with the "you don't need to be/show/have X to be Y!!!" type rubbish, a sentiment which forgets that if you don't show/have/be X then you ought at least show/have/be at least Z, W, U and V. Thus allowing anyone who is positively disposed towards labeling themselves as 'neurodiverse' or autistic the license to do so. Hell, you can even get yourself formally diagnosed, since you can just project yourself into the diagnostic criteria then borrow its language (without even thinking about it) so that any psychologist who wants for a bit of skepticism will be happy to give you the desired diagnosis. And if they don't? It's because they're just behind the times or narrow-minded or whatever, so you should just go see another one, maybe the one your penpal on tumblr got her diagnosis from.
I know this is a fact many of you oversocialised NPCs hate, but the day has 24 hours and mental stamina is a limited resource. We don't live in a perfect world of rainbow and bubblegum, I'm not going to mask for you, you're fucking dumb and I don't give a shit of how you may feel about it.