> the API was in the operating system and it allowed any app to be social. That was kind of the assumption that the PLATO people had.
Hmm, so why didn't the web emphasize social? Ponder...
Read-only web. The first web browser(s?) were read-write editors. HTTP GET was paired with PUT. But ramp up happened on read-only browsers (Mosaic, Navigator). User input wasn't possible until ISINDEX and then FORMs. Write didn't become part of the culture.
Documents, and separate social. In an ecosystem of ftp, and assorted file formats, and nntp (usenet news), there was a missing integrative piece. HMTL/URLs addressed that. Gopher had similar motivation. HTML was a static document format. But the 'one piece of an ecosystem' model meant social wasn't tightly integrated. If you wanted social, you did news, not WWW. You posted urls.
News (distributed social) plateaued, then declined, and the focus of social development shifted to web sites. I was never quite sure why news development stalled. There was a multi-year period, where it was clear what needed to be done to advance (eg voting), but it wasn't happening.
One certainly could have built a pervasively social system on top of the web. But it's hard for add-on layers to get traction. Even when they were part of the original vision. For example, X Windows' low-level Xlib, was intended only for the higher-level libraries everyone would then use, but those were slow to materialize, so everyone just stuck with Xlib.
Part of why the web worked was its initial simplicity and subsequent feature creeping. The hypertext community was quite miffed that this toy was getting traction, when their various more complex systems were not.
But we never got say a news2://... protocol. It seemed dotcom was pulling the oxygen away from a lot of potential infrastructure-ish projects - perhaps that was part of it.
Anyway, random musings.