Don't know what you mean by "distort"
Tommi Ahvala, David Chavez, even Fred Crossett made our Pro class better and raised the level of riding. If our guys can't or won't go to Europe then having them come here is a good option.
USA Motocross, Supercross, Road Racing and GNCC series all allow foreign riders and the series are better because of it. There is no benefit in isolating ourselves.