Worth recalling is the "primordial ooze" contained UnderNet, QuakeNet, TribalWar, PlanetQuake, 2ch and so forth; to this day, the likes of SA, 4ch, 8ch, Twitter and reddit are heavily influenced by gamer and anime culture.
I like how "memes" got laundered through these sites. Taking memes from adversarial communities and making them your own. Or blaming your own memes and campaigns on other communities.
There was, and still is, an admiration of the "hidden hand". Manipulating a newspaper poll, without their readers finding out about it, or blame hitting eBaumsWorld.
Memes started/start in small ICQ channels. Were collectively dumped online to seed them. Other communities would adapt, share, replicate, up until the point the real origins were obfuscated the meme was from "the internet".
Small hacker groups on ICQ had applicants write troll-scripts for acceptance. One of these was DuckRoll. DuckRoll consisted of switching out Wikipedia titles and article contents and sometimes adding a picture of a duck on wheels. Bonus points for having someone else run the script (thinking it was a PHP guest-book script, MySpace theme, or innocent link to an answer to their vampire help questions [1]).
Duckroll morphed into RickRoll. RickRoll was seen as more acceptable, since it contained the damage to a single individual. The principle was the same as with linking shock images, such as Goatse: either you knew about the image, and someone "gotcha", or the internet really confused and upset you that day. You probably were taking it too seriously, and the prank did you a favor. The best pranks had a lesson.
99.9% of those Rickrolled won't trace it back and think it started on Reddit or Digg, or simply "the internet".
Some of it is a desire for socialization mediated by a computer. Some of it is that PC gamers were getting online to play games and necessarily ended up having to talk about it (servers, patches, mods).
Something about the escapism, perhaps?