It is obvious from your reply that you may be one of those people who have opinions on everything.
ie. "I'm not familiar with that technology but I if my estimates are correct you might need to call function X to invoke output Y..."
XP is about evolutionary development. While prototype deployment is really fast coding to implement a feature, XP has certain techniques that allows for programmers to extend and refactor earlier code (the author was not clear on these).
Plus little bits of chaos injects fun into the workplace. :)