Yep.
It took me way too long to find the usage numbers (which ironically were within an arm's reach on my bookshelf most of the time), but ~1988 Usenet was under 1 million potential users, and fewer than 150,000 active readers. Even by the mid-1990s, it was under 1 million active participants.
Google+ was considered a failed social network with at least 10--100 million active users (by my own conservative estimates based on sampled profile data, independently verified by a much larger analysis). Facebook has 3 billion MAUs (monthly active users).
Until ~1992 (the Eternal September), Usenet users were largely represented as cohorts of a few hundred to low thousands, each subject to the disciplinary authority of university network administrators. Privileges could be and were revoked. Netadmins had a hardcopy directory in which everyone's number was listed twice (forward and reverse search). They talked to each other.
I'm active on Diaspora (for over a decade) and Mastodon (for about five years now). Both are far smaller than their comparable commercial equivalents (FB and Twitter, respectively). Each already strains under abuse, spam, and propaganda efforts, though Mastodon seems to have a more robust containment toolkit. Much resembles the old Usenet model: individual instance administrators can determine what users (locally or remotely) or instances (remote federation) can interact, and to what extent. It's high-touch, and has issues, but at present scale it mostly works. (Not perfectly, but it's not completely blown up yet either.)
Diaspora ... seems on far shakier grounds. User controls, admin engagement, reporting tools, and the culture of active management are all far weaker. The saving grace is the lack of algorithmic amplification, but bad actors are a distinct presence, if largely walled off into their own small, sad world.