Forgive me, but this is a silly argument: you could also point to courses in English literature or American history, which are very culture-speicif and pose high entry barriers to foreigners.
Just go and look how many Americans even apply to doctoral programs in mathematics, physics, engineering or business. After that, compare their quality to that of foreign students. At the next stage, see how many survive the program. But, if you want to skip all that, just look at the composition of faculty in any of the above or similar programs in any major university. In some cases, you will not find a single American teaching... marketing, for instance.
for courses where your argument might apply...in the long run you will basically have H1B professors teaching H1B-bound students.
And, this is supposed to prove... what, exactly?
I made a simple point. If I pay tuition, I'd like to be educated by the best faculty. If I pay for a symphony concert, I'd like to be entertained by the best musicians -- and they, too, are here on H1-B visas.
You counter this with a confirmation that I am in a minority: we no longer value education properly, and nobody but foreigners are willing to study "tough" areas. How is abandoning H1-B program going to remedy THAT?