It suppresses opinions that are not widely accepted or favorable and deters irritable tones of voice among other things.
Re: Ask HN: Does HN Karma do anything, other than give me dopamine? (in algorithm)
#31This is one reason I'm not a big fan of these sorts of karma systems. It's like when social media sites try to re-order the news instead of just showing it in chronological order. This post was popular, so maybe you'll like it too. Just a bit irritating. I think I prefer more traditional forums where the new posts are at the end.