Comment by abruzzi

Don’t forget that HN is also self moderated through upvotes/downvotes (I’ve never used Reddit, does it have similar?). This does two things IMO—first, low quality posts become less and less readable which reduces incentive to make inflammatory posts, but second it also imposes self moderation (except for users that resort to throwaway accounts) since losing too many karma points removes some of your ability to participate on the site.