Facebook democratized social networking.
At that time I don't recall the social networks being about your local community, friends and family like Facebook is today. It was about people you would never have met - because that's what made the Internet magical at the time. It could easily have morphed into forums of friends and family - not that it would have rivaled Facebook but it could have met the need.
Socially speaking, I think the Internet is much less interesting now than it was 20 years ago.
They solve different problems. Usenet of my youth provided way more value, both social and otherwise, to me than Facebook ever will. However Usenet would never have let me serendipitously reconnect with the good friend from high school I hadn't spoken to for over 10 years.
Facebook has the advantage of being a passive social network. If I stopped posting to Usenet (or twitter) for a month I essentially disappeared. With Facebook I don't have to do anything, people can still just as easily find and contact me if they want to.
There were like 20 years in between what you describe and Facebook's dominance.
Before Facebook there were thousands of thriving independent forums on wide varieties of topics. I spent large portions of my teenage years on them and got way more value out of them than I have out of any Facebook group.