> "internet based medium for socializing with people you know IRL"

"Social media" never meant that. We've forgotten already, but the original term was "social network" and the way sites worked back then is that everyone was contributing more or less original content. It would then be shared automatically to your network of friends. It was like texting but automatically broadcast to your contact list.

Then Facebook and others pivoted towards "resharing" content and it became less "what are my friends doing" and more "I want to watch random media" and your friends sharing it just became an input into the popularity algorithm. At that point, it became "social media".

HN is neither since there's no way to friend people or broadcast comments. It's just a forum where most threads are links, like Reddit.