I spend a lot of time in progressive (different from liberal) discussions and groups. I always avoid any discussion involving immigration because my views on the subject are quite similar to yours. A country that cannot control its border and who it allows inside that border is doomed to fail.

However, a country that allows immigration based strictly on the needs of business is just as likely to fail because it won't invest the money and effort to teach its own citizens the skills business needs. America has a problem with for-profit education and the level of debt required to meet the ever-changing demand of its businesses and its society. Obviously, a worker, whether it be a Dr. or a programmer, who is shackled with extreme debt from education loans cannot compete with one who obtained their education free, or on the cheap, in another country.

Pick an American city and scan the names on the list of medical professionals, especially specialists, and you'll find far fewer "American" names than one would expect. We can only be a brain drain for so long before we discover the price is not always as advertised.