The United States is one of the largest nations in the world in terms of land mass and there are thousands of counties all over the country that would bend over so far backwards that their spines would snap to enable real estate development for any number of Bay Area companies. T\he United States has a world class network of interstate highways that enables rapid motorized transit at high volumes in every state of the nation. There is also a network of third world caliber airports that are nonetheless serviceable.
The interstates are great for truck delivery and one-off trips such as moving/vacation, but a job is a daily round trip.
How far are software engineers really going to commute? If they don't commute, are they going to move to your 2nd/3rd tier town?
Some would but most aren't, so we see the same molasses drip of deceleration as companies that say they intend to hyper-grow stay stuck in a region that wants to hyper-stagnate.
Infrastructure is one thing. Human capital is the much more important factor for any of those companies.