East Coast vs. West Coast

I've worked in software development in many roles for 25+ years and I've had the opportunity to work with some fantastic engineers. One thing I've noticed over the years is that when I work with engineers who work for Silicon Valley companies, they tend to have a more rigourous process and stronger technical ability. The way they tend to look at the problem and their ability to apply different technologies is superior to most companies in my opinion. I recognize this is an oversimplification/generalization, but has anyone else noticed this? What about working for these companies makes for better engineers?