I don't see why you can't have the majority of active community performing civic duties.

Look at Stack Overflow. Most of active users vote down, vote up, flag inappropriate content.

Then, people become tacit at expressing their view, knowing they will not be sidestepped by a loud and inappropriate populist. This is compared to unmoderated communities, which turn into shouting matches and then the most fervent get permanent bans.

You can't create a community with a ban hammer only.