Being a waiter, working in a casino, being a cab driver, and running a coffee shop... you know, the secret to banning people is that you're always fair and more equitable than everyone else who's screaming, so when you do finally do it, everyone is either happy or scared they'll be next. People are surprisingly easy to manipulate this way. It would be wonderful if more sites activated that part of people's fear-lizard-brain more often; good manners are partly taught and partly enforced.

Yes you're right that it requires strength. And, at the same time, people have been training other people in every profession to do their jobs for ages. It's how we have survived and thrived as a species.