I suspect at least a part of increased tribalism is that, without visible comment scores, people aren't being shown as clearly that "that's not the HN way" and

I suspect at least a part of increased tribalism is that, without visible comment scores, people aren't being shown as clearly that "that's not the HN way" and "this is the HN way". On the rare occasions that a tribal comment gets downvoted to gray, this is often misinterpreted as "tribal downvotes", and therefore the tribe responds by upvoting (a power even new users have). As long as the comment gets back to 1, it appears the same as comments at 5, 10, or 100 -- so the tribe doesn't see how differently tribal and non-tribal comments are treated, and therefore doesn't learn the community standard. I think visible comment scores would help. I also think it would help to aggressively flag such comments, and to respond to such comments with "this sort of tribalism doesn't belong on Hacker News" (especially if that response was, visibly, upvoted to 10 or 20 points!)