[ChuckMcM]

Surprisingly you would find this isn't necessarily true. The reasoning goes like this:

Pool of available jobs is smaller, so the competition is fiercer, so the mediocre talent takes itself out of the game and all your are left with are the stars who don't want to move. I know lots of engineers in N. Carolina around the Research Triangle Park area who are way more talented than some folks in the Bay Area but they don't abide the culture that is Silicon Valley and so they don't move here.