This behavior is why the fediverse alienate users and makes it hostile for new people to join.
They didn't do anything, yet. Give them the chance but start with 2 strikes on their account already. They fuck up, THEN you defederate. Innocent until proven otherwise.
Edit: go on, downvote me. Show me your face. Show me how you're all against growth on Lemmy and niceness to each other.
And another attempt at blanket hating on a platform for no reason. Be more original, people.
Edit: if YOU don't like it, sure block it. But don't force your backwards decision on everyone else.