It isn't that HN is a random sample of the population, but that on most divisive issues (e.g. politics or programming languages) it's much more divided than people think it is.

Re disagreements and conflict, I'm talking about the comment threads, not the articles. I don't think articles really excite agreement or disagreement at themselves (except about whether they should be on HN in the first place—another divisive topic), so much as provoke it in the threads.

Re not feeling surrounded by enemies: that's great, but note that the "feel strongly about" qualifier is a necessary condition for this effect.