@jerry 100%.
One interesting idea I've seen floated recently is a "known-good" list(s), so a new instance can federate *only* with those on some known good list(s). Then someone joining a server can see if their server is part of the "X-approved list" and decide to join or not.
Obviously not a complete solution, but are we maybe at the size where it's a part of the picture? Make new instances prove they're good, rather than wait for them to prove they're bad?
@Crell it's antithetical to what the fediverse is intended to be, but it is a reasonable solutiion to this problem