Back in the day you had SHITTON of _GOOD_ new posts every day, stuff that you actually don't know even if you're at the top of the PvP food chain. Not visiting for a day or two == you're massively behind.
Nowadays you have, what.. Posts about vanilla servers every few days? But nonetheless, the habit of having to visit remains, so ye, addiction from the past. Although I never check this forum unless I'm at the very least casually playing.
I think a lot of it had to do with the fact that everyone was in High School or early college at the time, so most of this website was exceptionally immature and also had a lot of free time. All of the arena vets grew up, and there was never enough new blood to keep this website churning after that.