not essentially private per se, but usenet groups and bbs had a natural vetting because it required some competency to even access it

Listen while I tell of Christmas 1983, when every 14-year old with a VIC-20 got a cheap modem.

Seriously, haven't we been working tirelessly to expand the circle of access? Nostalgia reflects when the circle was smaller, and we felt that we knew everyone in it.