I wonder how pervasive this is on HN, since you need a minimum of 500 karma before you can downvote someone. I have to admit though, over the past year HN has started to feel more like reddit (this is not my first account, I have been here for many years). I don't think it's because of poor moderation, I think it's just a result of HN becoming popular enough that it's attracting a larger audience.