I’ve been successfully reporting troll-accounts and got them banned, I’ve blocked entire communities (mostly some niche-nsfw communities, so they don’t turn up in my local feed on my lemmynsfw.com-account). And I’ve found most community-moderators reeeeeeaaaaally don’t like fascists on their turf and if you see something and report something, most will get the boot.

Once an entire instance is gone though… defederate like there’s no tomorrow.