I think you might be experiencing the Baader–Meinhof phenomenon, bc I've checked through the last few days, there are a few anime memes, and like... 1 "porn" meme... So not exactly like this places is flooded with that.
I don't really feel like they detract or distract - anime is popular culture and that is gonna end up here and anywhere online where a bunch of sweaty nerds conversate... Same with porn.
Not trying to say "just block them" -- but, just block them? There are plenty of users and instances Ive blocked because I do not align with their values. It's a little work upfront, but your viewing pleasure will be better afterwards.
Or maybe I'm in the minority and the mods can weigh in.