I agree with 14k,
Millions of dogs and cats are put to sleep in shelters every year because there aren't enough homes for them all. God forbid we take responsibility for our actions (or lack thereof) but if fish_ could provide homes for 18 or so cats, and her first 3 were spayed, she (or her parents) could have rescued that many that would be put to sleep in a shelter.
Just because someone breeds purebred animals doesn't make them RESPONSIBLE breeders. Responsible breeders are dedicated to conforming to the breed standard. They have their breeding animals tested and most likely do NOT make a profit on them other than being able to feel proud of their happy, healthy dog or cat. responsible breeders take their puppies/kittens back from families who bought them and can no longer care for them. Pet quality animals aren't bred because they don't contribute to bettering the breed's lineage.
Backyard breeders obtain a purebred dog from anywhere- the shelter, pet shops, a friend, and breed their animal just because it's purebred.
So are purebreds superior to mutts? of course not. They, many times are healthier than purebreds, and no one is saying they arent equally wonderful companions. IMO a responsible pet owner who truly loves their pets will not breed pet quality animals if they realize what a problem pet overpopulation is.