Earlier quoted context omitted.
For what little it's worth, I've been online since Compuserve and personal local BBSs... I absolutely consider HN to be social media.
Mind sharing why? Is it the features or something else? When I think back 20 years to forums, HN feels most like those to me. It feels nothing like what most people call "social media"
To me, HN is just a well-maintained subreddit (pseudonymous, karma-based voting system, recency bias, etc.)