Greater connectivity amplifies the productivity of headquarters cities by enabling them to more readily project their power and distribute their output globally. With easy access to the output of Silicon Valley/Seattle/New York, there's less reason for each Nowheresville to have its own knowledge-work economy. The once-powerful bank manager of your local Chase is replaced by an algorithm in New York. The once-lucrative IT systems engineering work at your local manufacturer is replaced by AWS in Seattle. And so on.
[0] https://en.wikipedia.org/wiki/Economies_of_agglomeration