> Comments that go significantly against the political norms of the site seem particularly prone to this.
Agree, but notably, the political norms of the site are not distinctively left or right wing. There are any number of opinions that will get you downvoted here (unless your comment flies under the radar), and it really does not matter how thoughtful you are about it.
Example 1 (right wing): opposing gay marriage or abortion rights, opposing taxes, support for Donald Trump
Example 2 (left wing): anti-capitalist views, arguing that Richard Stallman should be removed, general anti-startup culture sentiment, (usually) opposing Elon Musk / Tesla
Example 3 (which side gets downvoted depends on who's awake): your opinion of Brandon Eich, universal basic income, your opinion of Apple (particularly socio-economic), unions
It's really not that surprising; the median Hacker News user is a white American man, wealthier and younger than average, with moderate liberal political views that skew libertarian on social issues. That's a "norm" of discourse even if it doesn't fit perfectly on the American Republican / Democrat spectrum.