alt Hacker News1990s IRC, Yahoo! and MSN Messenger were wild places. I don't know if those are considered social media. It's anonymous global Internet communications people have no fear of reprecussions. It's like a person in a riot throwing a rock there is no control and no fear.
Yes BUT nobody took anything on any of those platforms seriously. It was commonly agreed on at the time that the internet was for bullshit and bullshitting, and people reacted accordingly. The problems online didn't start in earnest until a bunch of people were convinced to pretend, in the face of overwhelming evidence to the contrary, that online spaces were a real thing where Important Stuff happened.