Imho, the comment visibility and ordering plays a critical role in this. It's pretty obvious first comments on HN that are generally upvotable tend to accumula

Imho, the comment visibility and ordering plays a critical role in this. It's pretty obvious first comments on HN that are generally upvotable tend to accumulate views, votes, and thereby become undisplacable from the top of the sort. In addition to drowning out lower comments as threads aren't collapsed. From a pure game perspective, not reading the article / skimming and posting a comment as quickly as possible strictly dominates reading the article, if you're optimizing for karma.