Those mediums do not have algorithms, feeds, followers, profiles, influencers, likes, or any features that many people point to as the toxic aspects of pretty much every commercial social media site of the last decade.
I’d say livejournal was the tipping point where the internet became very self-centered and your value in the platform was measured by how much engagement you were able to get.
Up until that point, in a world before blogs, social sites were mostly centered around shared interests and communities would aggressively police off topic content
Yes, no one was making that comparison.
In a generic sense, yes. People did socialize.
But "social media" today really means: a proprietary platform controlled by a single corporation, where all the user interaction is ultimately just a ploy to keep the participation metrics up so the corporation can profile you better and sell more advertising.
So in that sense, the absolute opposite.
The latrinalia of our age if you will.
Usenet was topic based (eg reddit seems closest these days), mail lists were usually topic based, forums were organised around topics etc.