I'd say a much more likely reason is that the enterprise can't get enough programers to support anything other than the MS stack. The culture at large enterprise simply isn't compatible with the hacker mindset. Banks are a notable exception in my mind, but then again banks have always been fairly agile when it comes to turning a profit.
Also, the open source ideal isn't an "indie developer" ideal. Serious systems engineering goes on in the open source community and it produces what often are the technically superior solutions.