I think everyone (or virtually everyone) is OK with actual world-leading researchers coming to the US. But what we don't want is the labor market flooded with foreign "talent". The system is designed to try to get the researchers and noteworthy people, but corrupt people have found ways around all of it. There are paper mills, degree mills, cheating rings, etc. Plus firms that exist solely to funnel foreigners into the US for a fee.

There is always an economic argument to be made for importing the cheapest or allegedly "best" labor, but it's mostly about saving money even if it means destroying domestic workers. It sounds better when we're talking about a scientist instead of a construction worker or meat packer, but it's kind of the same problem. There are many cases of American workers being forced to train H1-B replacements, or being blatantly discriminated against for being, shall we say, obviously American.

If foreign researchers are able to prove themselves abroad and contribute as you say, I assume they can continue doing that in most cases without coming to the US to take jobs. If immigrants are such a great resource, why are poor countries not trying harder to keep those people from leaving? Why doesn't China import a bunch of Indians for IT work, or vice versa?