>>35080540I don't know about danbooru in particular, but from what I understand, they were paywalling content just for greed. A big part of the big hentai sites that used to carry controversial content in the past, do no longer, because of German Youth protection NGOs.
Russia's Roskomnadzor used to also be a threat, but they tend to get the government to censor the sites for Russians, rather than actually going out and trying to get the sites to comply themselves.
It's quite risky to host NSFW content with user controlled variables in the current social climate, and I'm sure the devs don't want to deal with that shit.