I can't speak for FF.net, though I've heard it's mods are long since absent bar the most fundamental maintenance, but AO3 was specifically founded to avoid censorship as a rule after the fallout from LiveJournal and other sites
banning a bunch of this shit (though plenty more on top of that, good resource btw). The site's founder, Astolat, is noted for shipping Marvel's Thor and Loki and similar incest, and the broad establishment of the site's owners and donators typically support continuing the laissez faire policy. This leads to some seasonal shitflinging on Twitter whenever less problematically-inclined 15 year-olds relearn this, typically during the yearly donation drive though also every few months at random.
I'd say the most (/only, depending on your point of view) troubling detail about this is that
RPF (Real Person Fiction) is among the entirely allowed topics...
including smut RPF of actual, real-life minors. There's a horrific galleon's graveyard of this shit in relation to Minecraft youtubers, which has spawned it's own Twitter community "poppytwt", made up of minors (and adults) writing obscene fics about the "Dream SMP" cadre. I'm unsure if a thread exists on them, but it's a pretty substantial, grooming-rife community that's all but gone unreported since the big account documenting them was itself sunk by accusations a year or two ago. They're mostly private, and I'm not quite sure how many of them exist, but it's a ton. It could be an interesting thread, for sure.
Anyhow, though there's repetitive shitshows whenever anti-types remember all this (a supposed epidemic of racist and/or anti-lesbian fics in tags for Genshin Impact is another topic), AO3 has been pretty resistant to tightening up their policies. It worries me a tad as someone who's not entirely opposed to most of this stuff existing (it's often degenerate as it gets, but it's also one of the few places on the internet that somehow hasn't sanitized itself), but they've
really got to fucking axe the pedo-RPF. I'd wager that they can either get it done and accept a wave of residual slapfights at the announcement, or face a much worse apocalypse when some Vice journo needs a Monday headline and finds out that the most popular fanfiction site in the world allows this shit.
That could sink AO3, or at the very least most of the degen shit on it, so I'm surprised the mods seemingly haven't taken such a precaution.
Anyhow, I'm unsure about how much of this stuff, if any, has been discussed to death in this thread already because I'm new to it. It's a niche I fit, though, so I think I'll be here to stay, 'least if I come across anything notable.
Yeah, same boat. Not to powerlevel too hard, but I can't discount how many novel-length (if not quality) screeds I've come across for more than a few things I'm into. Hell, some
are pretty good, though for anything major you've obviously got to wade through oceans of shit.