Funny thing is that the original 'AGILE Manifesto' wasn't 'theory' or even a methodology: it was really a set of observations on what did and didn't work for them.
I think the 'universal solution' aspect of AGILE is let your smartest people work the way that they find most efficient - trust your (best) people. Many of the core concepts are not revolutionary: don't get bogged down in planning, work in small teams, prepare to adapt rapidly when your spec cannot be fixed.
The AGILE guys were inspired by the obvious wastefulness and inefficiency of the big enterprise software projects they had been on, so to that extent their observations were dead accurate. But now people are acting as though the *specific methodology* that's grown up around it is precious, holy and applies to everything, everywhere.
It's exactly like the scene in 'The Life of Brian; where Brian loses his shoe running from the crowd: one guy argues that they should all hold one shoe in the air, and the other guy wants to gather shoes together. The shoe is not the point (SCRUMS, Pair programming, backlogs), it is the idea of working intelligently.