Not quite. It's mostly not social media but there are similarities. There's a friends list here for sure where certain topics or people attract either similar or the same people. A small community effect happens there in the sub-threads. There's no private messaging but anyone posting an email or contact option will get messages if their posts are worthwhile. Anyone with HN Replies commenting a lot will have a pile of posts in their inbox on topics of interest. The last requirement mostly doesn't apply to decent members of the community but the sketchy ones dodge with with throwaways on a regular basis.

So, a bit closer to underlying mechanics of social networking in practice than it would seem on surface. Enough to get a similar participation high. That's on top of the knowledge expansion we use to justify the other high coming from the fact that we just enjoy reading this stuff. ;)

An I alone in never looking at usernames? I only read the content of each comment. I only look at the username to track a back-and-forth between two users and even then it's pretty much an opaque token to me. Might as well be a random string.

Your unconscious mind will see them. I don't know how much effect that has. I did consider helping people eliminate bias by creating a HN client that replaces the names with random ones on a per-thread basis. Any replies get substituted with real name when sent to actual site. Also some filtering options.

It is a sorta social networking though. A pull instead of push one, yes, but you do have feeds for people. Also, I recognize you and 'nickpsecurity by names already, by the very virtue of being a frequent visitor (and commenter), so it's not like totally anonymous - you get to talk to the same people over many discussion threads :).