Late reply: I'd intended to write "moderator removal", in the comment you're replying to.
That's a subtle but IMO meaningful distinction: HN's net moderation activity (participants, automated mechanisms, moderators) is not necessarily the same as that which occurs by staff moderators (admins) themselves, and much of the staff moderator activity is actually correcting for participant votes and flags.
This may be an overly fine point, but it seems worth pointing out. Particularly as any moderation system has its biases. But as I'd noted in my earlier reply(<https://news.ycombinator.com/item?id=49021366>), what HN achieves is a reduction in polarized commentary across the political spectrum, to an extent few other platforms have managed to accomplish. People on either side of multiple political divides seem to find bias against their own view, when the reality seems more likely that there's just not a wholehearted embrace of their perspective.
(That's largely my own take as well, though I think I've also become more skilled at presenting my arguments, and that perhaps as a consequence they're better received. I see disagreement, but fairly often support, even when arguing against what seems to be a prevalent or even majority opinion.)
What HN's net moderation system does (user flags, automated moderation, direct admin-moderator actions, shadowbans, penalties) is limit all extreme views, to the extent that they conflict with HN's Prime Directive, "to optimize for intellectual curiosity": <https://news.ycombinator.com/item?id=27901918>.
Challenges to conventional thinking are more than fair, but they've got to avoid falling foul of one of HN's guidelines, particularly increasing substantiality with time, thoughtful criticism, generic negativism, not fulminating, no personal attacks, not sneering (including at the rest of the community), good faith, responding to the strongest plausible interpretation of your interlocutor, avoiding flamebait / generic tangents / Internet tropes. And most importantly in this vein, not using HN for political or ideological battle (including nationalistic flamewars).
I don't always agree with mods, but I often do, and even where I disagree, I understand the underlying principles being employed. I've been an active critic / commentator on moderation for much of my time on-site (dating to 2011).