Performance is the most important and the paper helps you keep it going. Random dog to random bitch may produce a litter of fantastic workers or a load of crap, how do you know why ? Do you write the bitch off, do you write the dog off, was there something in the make up of both, that put together just didn't work but put to something else both could produce top class, who knows ! At least if you know the bloodlines, you have a chance to sort the problems out.