The way I see it, capitalism allows for any group of people to pursue any economic system, as long as they force it on no one else. Voluntary association, and the free exchange of goods between consenting individuals.
But groups of people don't function in isolated economic microcosms. Everybody is part of the same system. And while I think a free market is the best setup, there are major dangers for which I don't think America has succeeded in compensating. Some people get royally screwed with no way out. Plus, businesses will glob together to form forces so powerful they might as well be their own nations, and the government, which is supposed to be working for the general population, becomes the ***** of rich people.