Instead of being surprised at things over and over again, I think it's time to adjust our collective expectations to match the reality.
And yet it's still really good.
People like Larry Sanger prattle on about how awful wikipedia is (and make multiple websites for collecting mistakes, which mostly seem to be blank), rarely with any concrete evidence. In fact Sanger in particular refuses to browse wikipedia at all - except that he does but through a proxy, because giving wikipedia.org traffic is "icky". I pointed out that this is childish behaviour and he blocked me, go figure.
Stack Overflow is similar: you can make it look pretty bad case by case, yet it's an unchallenged best of breed despite its warts.
Maybe there's no perfect way to run these massive operations just like there is no clean, pretty answer to "should this article exist?" no matter where you set the bar.
"Decentralized" <> "unmoderated", "without content standards", or "without editors". Is there a more decentralized knowledge resource of general significance? Hosting happens to be centralized, only because nobody else cares enough to rehost it themselves (which the license allows you to do).