Is that a cause, though? I can see both as being consequences of the sheer amount of money sloshing around in the Silicon Valley. It generally helps things because there’s just so much resources to tap. It also helps employees getting poached with better salaries and compensation. But it does not mean that it can be replicated that way in another country.
You're right. It's not that disloyalty necessarily enables better software but that, apparently, loyalty is not a requirement.
It can also be true that the work culture in Japan stymies effective modern software development. I've heard anecdotes to this effect but it doesn't seem like something you could easily measure.
