The biggest problem I've seen over the years is that Wikipedia is not edited by experts, and in general is edited by losers.

These are the sorts of losers that watch the RSS feeds of the little kingdom of bullshit they've carved out in their own corner of Wikipedia and relentlessly fight anyone trying to edit THEIR articles. Until Wikipedia gives some sort of weight to experts (paid perhaps?) instead of unemployed shut ins, the quality will continue to deteriorate.