I think to some degree chickens are working animals like border collies and Australian cattle dogs. Those dog breeds are bred for their skill and performance and not conformation to a breed standard. Indeed breeders of border collies protested AKC recognition because they felt it would lead to a deterioration of the breed's working skills. Border collies are incredibly diverse in appearance. Chickens are raised for meat, eggs, and as pets. Any chicken that excels at one or more of those tasks is a good chicken as far as I'm concerned. I think the purebreds are beautiful and fascinating, but the overwhelming majority of chickens in this world are "mutts" and always have been. Most of us on BYC are fortunate enough to have the luxury of enjoying our chickens' personalities. In other parts of the world chicken eggs and meat remain an essential source of protein and I doubt hungry people care at all whether their dinner was bred pure!