Every side thinks HN is dominated by the opposite side. This is as reliable as clockwork. But the truth is boringly tautological: on divisive issues, the community is divided, like any sufficient sample of society at large would be.
People with strong views simply notice the comments they dislike much more strongly. And sometimes they pass around links to their friends to 'prove' it—which proves nothing, of course, but does strongly reinforce their perception. Once reinforced, these perceptions seem not to change.
On HN the divisions are exacerbated by this being so international a community. Only a third, last I checked, is in the US, and only a small minority in SV. So what we're all encountering here is not just polarization in the US, but much disagreement across national and cultural divides.
p.s. Unless I'm mistaken about the account, we didn't ban you. Nor have we shadowbanned accounts for years (except new accounts that appear to be trolling or spamming). When an account has been around for a while, we tell people we banned them.
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Edit: while I'm thinking about this...
Subtler factors exacerbate these perceptions too. HN isn't siloed—we have no subreddits, no following/blocking—just one big place where everyone sees the same things. Because of that, we're all more likely on HN to encounter comments from people we don't normally mix with, except perhaps on the battlefield. Reading what the 'other side' posts is not fun; it's painful. It gets right in your face and feels like being attacked. It seems to take only a few cases of this before it overflows into one's image of the site itself.
That association makes sense emotionally: I come to this place, I feel pain and anger, therefore this is a hateful place. But it's also just what one would expect from the numbers, which is why the reaction is so clockwork-reliable, as I said above. The people with opposite views to yours are feeling just the same anger and pain.
We see this not only about politics, but about programming languages, large companies, one's own work, and everything else people feel strongly about. We're all in one of those tricky spots where human feelings and statistics don't go well together, and for the most part don't realize it.