And HN is arguably better for not being invite-only. There are so many articles on HN where the top comment is by somebody with deep domain knowledge who provides some kind of original insight that fits into the low length and polish expectations of a comment, but would never have become a formal blog post. Invite-only communities intentionally give up on that kind of discourse for... what? Easier moderation?
I think that when our reputations are on the line, that we act much better but also discard the grit and sharp edges that are the catalyst for interest and growth. I believe that we begin to converge on a single, aggregate pseudo-personality that is the most accepted register for communicating within. Karma points enable this convergence because they are the only metric that we can do data analysis on comment quality…
Most of the time when I see unproductive conversations go back-and-forth here, it's often clear (or I'm quick to give the benefit of doubt) that at least one of them is a newbie trying to meaningfully contribute to a conversation where they don't know how much they don't know. But there's a sizable number of posts where I'm convinced the poster is a passive aggressive asshole that knows exactly the game they're playing. As long as they can hold a conversation with the surface level appearance of someone acting reasonable and polite, they get to be wildly disingenuous and/or cut people down nastier than the kind of comments that would be immediately moderated away.