I have noticed this trend as well. That is why I read HN with dead comments enabled, and vouch+upvote a dead comment whenever I think it adds to the discussion

I have noticed this trend as well. That is why I read HN with dead comments enabled, and vouch+upvote a dead comment whenever I think it adds to the discussion (e.g. brings new info or brings up a point or angle that I haven't seen in that thread and makes me stop and think about it for a second or two), regardless of whether or not I agree with that comment. Sometimes good comments end up forgotten, just because someone got to them first, who disagrees with them and is not intellectually mature enough to handle that.