One of the signature Wiki features is that people edit pages over the web, often anyone and without restrictions (as the original Wiki was/is). It's said that this is a defining trait of Wikis, and that without it what you have isn't really a wiki.
A web browser's form input text boxes are a totally crappy editing environment compared to what I have on a Unix system. Yeah, sure, I could require Javascript and load a huge editing library and maybe get somewhere, but a) I browse with Javascript off and b) am I going to get half as good as GNU Emacs or vi or sam? (I don't think so.)
The principles of global edit permissions leading to the world help write your pages simply don't make sense for us. DWiki's goal is to let us easily document how our Unix systems work. We're the only people who can write most of that documentation; outsiders can at best add side commentary.
This would be different if we were interested in running a Wiki on system administration best practices or the like. But we're not; we're just documenting our systems. We let other people read it so that they can learn from anything interesting we do (and that's primarily aimed at other people at the University of Toronto).