Someone killed the redirect because it was in article space.
The original article is here: http://en.wikipedia.org/wiki/Wikipedia:Why_Wikipedia_is_not_...
So does Wikipedia let you look at deleted pages? I thought they did but from the article link I couldn't find it.
edit -- I was thinking of this: http://en.wikipedia.org/w/index.php?title=Why_Wikipedia_is_n...
I guess not.
This page has to be deleted and undeleted by admins, yes? So editors with privileges are helping to write this and reinstate it from time to time? Interesting.