I've been knocking about social media since the '80s
Forgive my ignorance, but how?
I didn't see my first web browser until around '94 and social sites didn't arrive until nearer the end of that decade? Was I just very late to the party?
I guess you are not aware of Usenet. It was arguably the first social media system and commonly used by university researchers and such.
https://en.wikipedia.org/wiki/Usenet Yes, like many I discovered Usenet by typing rn instead of rm. Our department feed came once or twice a week via tape until we got our own Telebit Trailblazer modem.
The oldest post of mine I can find in Google Groups is from March '88 in comp.sys.mac.hypercard. I later found rec.motorcycles and became a Denizen of Doom.
In 1990 I started a UK motorcycle email list which is still going strong having changed host a few times and after a rename for legal reasons.