Comment by quanticle

    Wales is right about one thing, though. This fact does have enormous policy
    implications. If Wikipedia is written by occasional contributors, then 
    growing it requires making it easier and more rewarding to contribute 
    occasionally. Instead of trying to squeeze more work out of those who spend
    their life on Wikipedia, we need to broaden the base of those who 
    contribute just a little bit.

The problem is that, as a community, Wikipedia has gone out of its way to do the opposite of that. New content is often treated as "guilty until proven innocent", and it's up to the contributor to wade through Wikipedia's idiosyncratic rules and definitions in order to justify to the moderators why their edits should not be reverted or their articles deleted.