We need to crowd source a common list of instances to block from users and mods across the network for instances to use, like people on Mastodon started doing. It was really effective. Defederation is really the only way to deal with / only check on users that sign up on instances that don't moderate them at all in order to harass others with impunity, since moderators can't effect users on s different instance and so it basically gives such users free reign. That's why IMHO defederation is a REALLY crucial tool to make this place livable, otherwise it'd be filled with trolls doing their thing with absolute impunity and there would be nothing mods, who are supposed to be the first line of defense for that kind of thing, could do,