That goes against most everything in international economics. A nation doesnt have to be "complete." If we were complete, we would produce every single good and service that Americans buy. 1) thats not possible, we simply dont have the capacity and work force to do it, and 2) that would make those goods and services more expensive.
Specialization (ie, competitive advantage) is the reason we can buy stuff at Walmart for half the price of its American-made counterpart. You build what you excel at, and Ill build what I excel at. We'll import/export the rest and we'll both be better off because I will be able to supply you my goods for less than you could produce them on your own. Thats why China, India, and a lot of Southeast Asia is growing so rapidly, they have a competitive advantage in terms of really cheap labor. Why pay some American union worker $25/hr to do something that a little Asian man can and will do for $2.75/hr? You dont. And its part of the reason why the American auto industry is dying. They never adapted to change, and with a global marketplace if you dont change you will die. GM is a perfect example of "Im king of the hill....oh shit, here comes Toyota. Im king of the hill" (as Toyota is kicking GM down the hill).