I have been batting around the concept of a federated algorithm that works akin to Herd Immunity
Through Consensus, communities should be able to individually choose to block a specific community, and then you can configure your community to block a community if enough of its trusted communities block it as well.
So if you have 10 trusted communities and 8/10 of those have blocked community A, then you will also block community A implicitly because you trust them.
Summarized:
Bigots are astonished to discover they are largely unwelcome in society and that their actions have consequences, and that the majority of people (especially in places like a debate club) are not interested in giving bigots a platform.
Later tonight: Sports Celebrity is astonished to discover that even though he is really good at <sport>, he is kicked off the team for criminal actions earlier that week.