I don't necessarily think this is accurate. I've observed a strong and useful pattern here where posts are deconstructed in the comments in a logical fashion which I believe is, and should be seen as constructive.

Even if you come down strongly on one side or the other of a topic, it's a good discipline to look for logical weaknesses, edge cases and other potential holes in any given argument.

HN is great for this because for any given post you can typically find well thought out rebuttals which may or may not sway your opinion, but will in many cases be instructive in the very least.

Of course, the other option is to simply attack the commenter directly and fail to learn anything at all.