I come to Hacker News not only for the submissions but more so for the discussion. I find as of late discussions populated with meaningless content. It seems people feel a need to communicate what they are thinking regardless of the comments usefulness.
I fall prey to this too. If my comments are short I do try to make sure they are helpful in some way. I will try to keep them on-topic and not filled with worthless opinion.
Yep. I feel like my first mistake on this site was to argue with every comment I disagreed with. Unless the comment leads to an instructive discussion, it's OK to just downvote it.
For a site that is ostensibly focused on intellectual curiosity, this is antithetical to that goal. A robust, informed discussion requires exposure to a variety of perspectives, especially ones that seem challenging or uncomfortable.
If you do not agree with a comment--so what? Either refute it or move on. Just because you are unable or unwilling to refute it does not mean that someone else will not come along after you and do so. Downvoting should be reserved for comments which are truly useless, not comments that you merely disagree with.
And, yes, I am aware that downvoting for disagreement has been promoted and accepted by some on HN, but it's wrong--at least, it is if your actual goal is to have robust, informed discussion of intellectually interesting topics.