It might be cromulent to some, but in my experience it is not widespread. Definitely done at a much lower rate than other places like reddit. Main indicator of this is that on HN it's not uncommon to see an upvoted comment that has almost exclusively argumentative replies. However on reddit when I see a comment with so many disagreeing responses, it's well into the negative.

Also, at a sample point of one, I make an effort to never downvote because of disagreement. I don't behave that way on reddit. Something about herd mentality perhaps.