AND it's not like breeding is necessary to get healthy dogs, there are some very healthy animals out there(and we generally don't have a 'wild caught' problem with dogs) They are domesticated animals, not being taken from the wild.
Some animals should be bought from breeders, some you shouldn't. It's considered better for reptiles in general if they are bought from breeders--pet stores usually have wildcaught specimens who are taken by people who don't care for their health. They then even overcharge for them(leopard gecko for 45 dollars, a healthy normal morph baby from a breeder is more like 10 dollars) and then expect them to die anyway!
Same with birds, it's not a good idea to buy a bird from a big chain petstore, if at all possible, get one from a breeder. You can get them handfed, loved and played with, and it is not a scared wild animal who feels trapped now that it isn't outside!
I have a purebred dog, I had a pure bred cat, but I love getting animals from shelters too. Honestly though, there is a myth that 'mutts' are healthier than purebreds--while this CAN be true, it can also be VERY false!! We had a mutt who seemed to have every health problem that each of his parents had. He had seizures like his boxer mom, bone issues like his golden retriever father.. It was a very difficult dog to take care of, but I loved him. There actually are some purebred dogs with very few if any natural health problems--the closer they are to the original 'dog', the healthier. Also seems the ones less popular(not bred for looks) are the ones that are healthiest... Maybe because the only people breeding them do it for the breed, not to make money?
Edit: Oh! It seems 1fish2fish and I agree on the dog issue!