You have somewhat of a valid point except that few steel companies in the US are solely owned as US companies. They tend to be subsidiaries of foreign companies.
So buying American will mean profits going overseas. You may also want to consider that the same form of protectionism was employed during the Great Depression by FDR for the steel companies and it did result in protectionist tariffs against American goods being sold overseas. Problem now is there are very few true just one country companies so for foreign governments to impose high tariffs would be cutting their noses off to despite their face. Don't you just love globalization.