I'm taking the opposite approach, that is, instead of blocking what I don't want to see, I join what I do want to see.
Blocking is not effective if you want a "curated" feed IMO, new communities are being created all the time, especially now that many are migrating over from reddit, you might never "end" blocking stuff.
OP post is a different situation though, that kind of content is illegal in many countries (especially EU), just being federated with them could pose a legal risk, it's not just stuff some people don't want to see.