I don't think HN is monocultural, at least to a pathological extent. There's quite a bit of debate here. The overwhelming majority of grayed out comments are baseless, off-topic, or unnecessarily inflammatory, from my perspective. I think that's because there's a norm to agree with an upvote, disagree with a non-vote, and reserve downvotes for unproductive commentary. People seem to upvote unfairly gray comments regardless of their personal agreement.