If you don't want to see something from someone, you can just mute them.

Allowing for account bans opens up a whole mess of worms. Destructive to the ecosystem.

Trolls will always have a voice... it will just be worthless here, and noone will care what they're saying.

Better than an alternative, like Facebook or Twitter where a faceless entity can ban your account for not abiding by the Political Correctness codes of the moment.