It can also be argued that one of the great things about America’s ideals (alas, not always its reality) is a belief that achieving the American dream is not based on who you are. In contract, some very fine cultures definitely do not work that way.
For example, the French have historically made a clear distinction between those who are French and those who are not. Japan is similar in that regard. I think that these are simply the natural consequences of having a long history as a monoculture.
But America has never been a monoculture. And therefore the idea of who can be an American is far more amorphous — a natural consequence of its particular history.
Other than Native Americans, whose ancestors have been here for tens of thousands of years, America is very much a nation of recent immigrants. Nearly every American you know can easily trace their roots to somewhere else in the world by going back just a few generations.
America is therefore necessarily an amalgam of many cultures and many ways of life. So the entire franchise can only operate, pretty much by definition, by being inclusive.
When you look at it this way, it becomes clear that America’s principle of inclusivity is one of its greatest strengths. More tomorrow.