The thing is that professors and research groups aren't fungible. Each one that moves represents a nontrivial loss in expertise for the US in some field. There are only so many groups doing basic research into materials science for microelectronics, for example---certainly not at all 187 R1 universities. But something like that is a strategic asset for the US, to the point that there's a DARPA office specifically to fund that work (https://www.darpa.mil/about/offices/mto).