As I see it communities nowadays need a way to exclude a-holes or else the community will eventually evaporate since staying is not worth the cost of putting up

As I see it communities nowadays need a way to exclude a-holes or else the community will eventually evaporate since staying is not worth the cost of putting up with the a-holes. I say nowadays because as I see it the cost of creating a community has gone down and the number of options has increased. As a result people won't stay around in a community simply due to lack of other options. So at it's core the question is "do we have a process for doing this removal" or "do we leave it up to the pure discretion of whomever controls the block button."