HN allows a very wide swath of opinions without over-moderation. I've seen arguments commonly from every ideological & political segment, even though HN leans left (because its userbase foundation derives from the Bay Area, which is 95% left leaning). You see Capitalists here, you see Communists, you see conservatives, you see liberals, you see libertarians, you see every flavor of Socialist, you see everything inbetween.
You can argue for most points of view here, so long as you remain within their decency guidelines. Obviously HN won't tolerate certain extreme ideas that involve genocidal camps, killing people, violence or racism, that you might see bubble up out of eg the pro fascist or pro communist camps.
If there are 20 slices in a gradient of political ideology in the US (as an example), HN will allow you to very freely argue 18 of them, only dropping the extreme left and right (both of which commonly involve arguing for murder, racism, genocide, oppression, gulags, forced re-education camps, violence and countless other horrible things).
If you go into the largest political sections of Reddit arguing strongly (but decently) for Trump, you'll get moderated because the mods won't like you. That doesn't happen on HN, Dang will mostly leave your opinions alone (you will get downvoted though), so long as you are arguing in a way that isn't belligerent.