That’s a pretty general statement. I can’t speak for other countries, but here in the US, breeders breed for health and temperament. Genetic testing, hip and elbow certifications, pedigrees...it’s all for breeding a healthy and happy dog. Yes there are some outliers, such as pugs. And GSDs have had a terrible breeding history. But any reputable breeder, which is ideally the type of breeds you would purchase a puppy from, only and exclusively breeds for their pups health and temperament.
You have to understand 2 things about breeders:
1: They are a business. And they won’t stay in business selling sick or unhealthy puppies. Backyard breeders can and will try but they always fail, and reputable breeders who breed quality pups stick around.
2: The whole point and purpose of dog showing, is to show the ideal specimen of a breed. That means perfect coat, perfect gait and structure, good temperament, receptiveness to training and a whole bunch of of the criteria. The literal purpose of dog shows are to show the best of the best of the breed. That’s it. It’s not a for profit thing. They are NOT bred to look good. The AKC does not mess around when it comes to this stuff. You cannot show an unhealthy, poorly bred dog. Nor can you be backed by the AKC if you chose to breed said dog.
My recommendation to you: if the pups health is as important to you as you make it seem, which it very well should be, stick with an AKC breeder, assuming you’re in the US. The AKC has tons of resources and help available to help you find the right breeder. A puppy from an AKC breeder will come with a pedigree showing multiple generations of ancestors, numerous healthy checks, genetic tests clearing the pup of genetic diseases such as DM, the OFA certifications of the parents as well as their genetic tests, and most puppies come with a health guarantee, where if say the poor pup developed severe hip dysplasia at 6 months, they may help cover the cost or offer you another puppy, every breeder is different. Do some research, getting a mutt because you think it will be healthier is completely backwards.