I actually think HN achieves the illusion of greatness via excessive moderation. It’s very easy for users to flag a topic from the front page and (IIRC) there are even automated downranks for threads that attract a lot of back and forth arguing.

The result is a site with relatively measured debate but also a large chunk of missing debate. All that said I don’t have some genius idea about how to do it better so my criticisms can only go so far.

Sure, some debate is missing here. But I think it's fair to posit that the debate in question is of low value, and that we're better off without it. Or, at worst, that losing it is a wash in the grand scheme of things.

In either case, the owners/operators of HN set a standard for the kind of discourse they want to encourage, and they take steps to encourage it. Nothing wrong with that. Reddit, Slashdot, 4chan, Twitter, and countless other sites exist for people with different tastes.