I must agree with the parent commenter: HN is social media.
Oh, maybe it's not exactly like facebook or Twitter, but it ticks so many other boxes.
I could list many, and argue about them (arguing: another staple of social media), but the most important to me is that HN is effectively a procrastination tool, and it's associated with that mental "fix" of instant gratification.
It's different from facebook in that HN is more heavily moderated and more focused, but other than that, it triggers the same kind of (bad) habits, at least in my case.
You are free to pick a different definition. "Permits arguing and procrastination" would make it a pretty big category, including all online forum and chat systems back to the Usenet / BBS and maybe CompuServe / Prodigy days (I don't know enough about the last two).
Usenet seemed more social than HN, as I remember it from the 1990s. You'd go back to the same groups, and see the same people posting. On HN, I don't usually see any name I remember.
Regardless of whether it's social media or not, HN is a huge digital waste of time. Try to think of more than 10 posts that really improved your life over the years. Now realize that you probably look at more than 50 HN posts a day. I would spend much less time on HN, but it's an addiction, like most things digital.
My experience has been different. I consider HN to be a kind of 'finger on the pulse' for my profession as a programmer, and in that regard it's fantastic.
Reddit, on the other hand, is a huge time sink (some good, some bad, I read an awful lot of short fiction on Reddit, and I consider that a positive).
I can think of dozens upon dozens of posts that were useful over the years! In a way HN has reduced the amount of networking I have had to do in order to see what people are interested are in, as they are posted here!
