It's offtopic, but when you reach 500 karma (or thereabouts), you get the ability to downvote the comments you feel are a net-detriment to the discussion. Sometimes, when I express a particularly unpopular opinion I also get flagged. The result is what I call "the doghouse", it causes comments to sink to the bottom like stones for a few months, among other things. HN moderation has hidden mechanics and the results can be very frustrating. But in 99% of cases, when those special mechanics are not in effect, the system works pretty well.