Process is an embedded reaction to prior stupidity.
A wiki in the hands of a healthy community works. A wiki in the hands of an indifferent community fails...
And an example he gives: some graffity entries on site http://wikitravel.org/ were removed in less than two hours.
Ben Hide has some interesting counterpoints on why processes are required:
The challenge in making a community that functions well is creating something out of those talents that is closer to the maximum over the diverse talents rather then the maximum of their lack of skills.
Processes are required to create a "minimum standard" for a particular task, especially when a person is new to task. These are available through checklists and templates, references collected etc. in previous similar tasks. In my experience, I have seen that if the task we are performing has "wiki-enabled" people, there are lot of optimizations: We already work against checklists, quickly gather relevant details in one place, and in general, meticulously manage the information through the task.
But if there were other people, it is usually a fallback on email-enabled communication (and a lot of meetings thrown in). While we can't really compare the quality of the results, the overall experience is bit more taxing, involves more time. There is never a sense of "having taken care of it all" and "Am I missing something?". I have sometimes forgotten simple tasks such as spell-checking after "queuing" it to be done before submission.
I used to often forget the mobile charger before an important travel. But now, a 'travel checklist' that sits in my home wiki takes care of these things!