Reddit's best big technical communities are better on this regard too. Their moderation is more transparent and dependent on volunteerism, and somehow even the more serious communities squeeze in more humor.

Also, HN gives you the vibe such that you'd wish to argue about the orthogonality of empathy and signal? As opposed to HN feels like SO?

Do they actually though? If you have empathy for the people in your community, are you not more likely to contribute more meaningfully to that community (I.e. more signal)?