given that the biggest software companies of the last 20 years have mostly been in the Bay Area, maybe there's a flaw in your assumption that there are "more experienced people pretty much anywhere."
I think that has more to do with the VC cartel than the amount of actual talent. Besides, the cost of living has heavily changed over the years, and the amount of feces and dirty needles on SF streets have increased rapidly lately. Talented people are more likely to realize this is a farce, and leave the area. The historical circumstances may not hold true anymore.
