For those us whose Internet citizenship pre-dates Friendster and MySpace, the term "social media" has a particular meaning.
But for many younger "social media natives", the term basically just means "any website or app where you can make posts or comments".
When I think about it, it seems like a somewhat arbitrary distinction to make. I suppose the main difference is that the forums were self-hosted and I could have different identities for each one. And while I generally reused the same username, the fact that it wasn't just a matter of 'clicking on my profile' to see all my activity was something I really liked.
Maybe to me the term "social media" has come to mean "social media /companies/"? That doesn't quite satisfy, but it really does feel like the primary difference is that on these forums I knew that they were generally not run for profit, and the 'gods' were just individuals who volunteered their time to host or moderate. It felt safer, and more personal.
You are right.
There are big diffferences.
For one: You can joke on TikTok ...
Choke not joke...big difference
Closest I can get to HN ⋂ dancing is 1:34-1:48 in Virus' "You should ask" (where the video is about the difficulty of source attribution on a LAN, let alone an entire internet)