Throughout the history of the US, fine, especially when medicine was not deemed to be as attractive an opportunity as it is today, and the supply/demand imbalance between seats and candidates wasn't so striking. In today's "dysfunctional" (as you pointed out) and xenophobic environment, it's probably a bit much for that view to have widespread support in the country while there is a surplus of highly qualified American students who cannot gain entry into American medical schools.
In any event, providing highly qualified FMGs an opportunity to practice is very different from having taxpayers create more slots so the SGUs of the world can make even more money. To bring the conversation back on point, yes, American seats increased 30% over the past decade, and yes, residency slots have increased at a slower rate, and, yes, there is still more than one residency slot for every American medical school seat, so, no, Congress is not going to make up the difference, and yes, that shortfall will cause there to be less slots for IMGs and FMGs.
The present day trend appears to be to create more American seats, and not to create more residency slots for Caribbean graduates to fill. Given the high admission standards of the Caribbean schools, this is not a terrible thing. It would be to the benefit of the population that we increase American seats and residency slots to address the shortage. Let's do that and watch the fireworks begin as supply begins to meet demand and physician incomes react the way the free market dictates that they will when a supply/demand imbalance is addressed.
Shorting healthcare for our own citizens has probably been a goal of the AMA/AAMC/USMLE (or whoever is responsible for gate keeping the profession) for as long as you have been alive as a means of protecting physician incomes. Otherwise, why the hell has there been a doctor shortage in the US for forever? A lack of domestic interest in the profession? A lack of qualified candidates? A lack of resources to build schools? A collective lack of the necessary intelligence to identify the issue and address it? Or maybe, just maybe, by design!!!