I first discovered the 'net in 1995; purely by happenstance I clicked on something called "Excite" and found myself involved in a massive message board that I never did find the edges of; there were sections for everything from politics to religion to literature to build-your-own, and the day someone actually responded to a comment I made, I was hooked. I don't think in the next year I watched TV for more than an hour a week. And after that almost never.
What appealed was the interactiveness of it, something that I think we all take for granted now; and to watch TV after that was numbing. Sit, stare, react, lather, rinse, repeat.
And when I finally encountered a real debate I suddenly realized I had no idea how to react, how to respond, how to comment. It had been probably 30 years since I had had a deep convo about anything, and suddenly here they were, all around me.
I also encountered my first online sociopath, my first flame war (hello Harvey) my first friends (hello Harvey) and discovered the arts of diplomacy, debating, and role playing.
I miss the structure they had then, and the breadth. Message boards became forums, and then splintered off into specialized arenas; now we have a dozen or more kinds of ways to interact, from blogs to games to specialized forums to social networking. I dont miss the flames, but I do miss the people. Even the stinkers.