I think one of the key aspects of the dialup BBS days was that long-distance connections were (sometimes very) expensive, and so BBS systems tended to be popula

I think one of the key aspects of the dialup BBS days was that long-distance connections were (sometimes very) expensive, and so BBS systems tended to be populated by locals. There were some networked BBS systems, though (FidoNet and WWIV spring to mind). I played around with FidoNet back in the late 1980s/early 90s, when Usenet was not available to me, and FidoNet's Usenet-like echomail system had some very active groups. But even with FidoNet, there was very much a local-to-regional focus. Networks were organized geographically, and Net 115 (Chicago area) had some social gatherings. But FidoNet collapsed pretty quickly once the internet came to the public.