(I didn’t, largely since I’ve never watched a single episode, but the psychic damage and whiplash of Wholesome Pony Show having said this line was too fuckn much for me)
EDIT: More replies than upbears now. It’s probably an official struggle session now (although most of it is that one person). One must imagine SisyFEWs happy.
Remember that a big chunk of the historical fandom was weirdo fascist edgelords who wanted to fuck the ponies and wrote horny violent fanfics about them. One of the longest fanfics about anything (FOE:PH) is basically “Made in Abyss but it’s ponies and set in a post apocalyptic wasteland.”
Oh God, I remember hearing talk about how terrible this was and having a peek out of morbid curiosity. I made it maybe a quarter of the way through the first chapter before I had to dip out at the exhaustively described fever dream of what MRAs imagine a society run by feminists would look like.
Wasn’t there also a Fallout crossover fanfic that completely missed the humor aspect that was always present in Fallout and was sort of edgy for edginess’ sake? I never read it, but its fandom was pretty
at a glance.
That was all of the Fallout crossover fanfics
The most infamous of those is the one I mentioned, Fallout Equestria: Project Horizons, but the original Fallout Equestria was also pretty bad just much, much more tame than FOE:PH was.
You said it’s related to Made in Abyss so I take it there’s a lot of
factor too. 
It predates it, but it is similar in tone and grotesqueness. Although thinking about the full depth of the problems with Made in Abyss that I covered exhaustively in a post last night, FOE:PH isn’t as bad. It’s a gratuitous, edgy spectacle that handles problematic themes poorly, but it’s merely making an exploitative spectacle of them while Made in Abyss is even worse. AFAIK most of the characters in Project Horizons are adults though, though I think there’s some nonce stuff in there too.
I have no idea why you read it, but I assume it was something like this as a situation.
I compulsively consume problematic slop, and was even worse about it a decade ago when I was in the process of rebuilding my schema from the ground up after dismantling twenty years of calcified repression brainworms, which is around when I read part of the then-incomplete FOE:PH specifically because of its reputation. Made in Abyss has to be the only thing that’s actually made me sick to watch, however. I can’t emphasize enough how even the people who condemn it undersell just how vile it is; it’s in a league of awful all of its own. Like I feel even my “Made in Abyss is the worst thing anyone has ever made” rant is too soft, because I couldn’t stomach really dredging up the specifics.
From what I know about it, there’s a blurry line between “presents and does not condone, and maybe didn’t read the room and has hogs eating the slop now” to “presents and claims it does not condone and it’s clear the makers are also the hogs.”