Here’s a post on how community-driven sites like Digg succumb to their own popularity.
The idea is fine, but one thing is forgotten… People are sheep. People don’t vote things up they disagree with, don’t like or don’t know anything about. So we see a kind of convergence. The stuff that toes the community line, that most people agree with and that doesn’t challenge people too much gets voted up, whilst the stuff on the fringes, the niche stuff, disappears. The community attracts people who enjoy its content, and so content becomes stale, repetitive and dull.