Self-documenting or not, I think the point stands, the standard stuff is very well documented via many means (a nice tutorial, a very comprehensive manual, an emacs lisp tutorial and an emacs lisp reference all ship with Emacs in addition to things like describe-function, describe-key, describe-variable etc.), so the role of the Wiki is to supplement those and not replace them.
Really? The splash screen (literally the first thing that appears when you first run Emacs) has links to 3 key pieces of documentation: 2 tutorials and the reference manual, which is surprisingly comprehensive. It would be really hard for them to be more upfront about the documentation.