Your argument does not hold water. A ball python bred to a ball python does not create mutts. A ball python bred to any other species does. Just because a ball python has a genetic mutation (color / pattern) does not mean that it is not a ball python, therefore, breeding it to another ball python does not create mutts.
My thought on hybrids is that they muddy bloodlines. I do not want an animal with muddy bloodline in my breeding stock. Anyone that sells hybrids increases the chance that breeders who feel the same way I do will end up with animals with muddy bloodlines.