World class athletes often compete at a similar level.

Right, and as the selection process is about the same everywhere, based on national, continental and world championships results, world class athletes, whatever European or American, are already ALL qualified for the games.
Sending multiple American teams would just allow the US to send more non-world-class athletes like individual European countries do.
I could name you dozens of American and European athletes who go to Beijing and whose best performances are absolutely not world-class and who have no chance whatsoever to win a medal.