HN is a very strange beast. I do rather enjoy it, though.

I think what you're noticing is that a simple left/right along a line is a poor way to express someone's political views.

I suspect that because a huge portion of the HN crowd are educated IT workers / would-be founders, overall there's both a strong support for capitalism mixed with progressive social views. That doesn't really connect well with the political landscape in most of the western world and typically gets you labeled a centrist, regardless of how important those particular issues are to you.

What you say is partly true, but it goes beyond that. It's not that uncommon to see even straight up anti-capitalist comments here that still get upvoted, or the kind of "market solves all" talk getting downvoted into oblivion. So I'd say there's a hefty chunk of the userbase that is also leaning strongly left economically.