Why? I think this approach makes an assumption that everyone is upvoting everything that they would not downvote. I upvote things I find interesting or insightful, and I do my part in terms of moderation by downvoting comments that don't have a good fit for HN.
What I see on Facebook and Twitter is that the inability for the hivemind to have some kind of downward pressure mechanism on comments encourages/enables polarizing comments by vocal minorities to rise to the top. I see this frequently in the comments on the posts of local political figures. The top comments shown are almost always controversial and unhelpful/unproductive - things like whataboutism, blatantly racist remarks, etc. Eventually I got tired of constantly catching myself up in arms over FB comments and stopped participating.
The only way I see to counteract this as a rank-and-file user is to upvote/like every single comment except for the ones that are hurting actual discourse. IMO this will drive away people that you ultimately want to be participating on HN.
