(I'm the author) Well...yes...and that's where (I hope) most people will start. What happens next, I've found, is that people's own confirmation bias' kick in, and they take the manifesto and make it describe (in their own mind) what they are already doing and/or want to do.

The manifesto (to me) is how people who understood the nature and goals of Agile summarized their sprawling, complex, interconnected - and valid - thoughts. At the risk of being hyperbolic, I think of it like E = MC^2. Yes, that is a good summary of Einstein's theories, but if all you ever know of them is this summary you'll miss all the implications of what happens when you put it into practice. Probably a terrible example, but the best I could think of.