Earlier quoted context omitted.
Ratings already take care of curating. Why do you need assholes to curate?
Same reason why HN has both up/down votes, and actual moderators.
This separates the good from the bad
> and actual moderators
This stops the trolling and spammy pump and dump comments/posts
It works pretty well. I've never felt unwelcome on HN, even when something I've posted gets downvoted. I come away with a more "ehhh, yeah I get it" feel rather than anything resembling the bitterness I feel whenever StackOverflow is the only option in search results.
Give people powers based on how much they use a site and they'll just start pushing people out of the site. It happened a lot back in the day in IRC, happens all over Wikipedia, happens all over StackOverflow. There's a pattern.