Different breeds have different characteristics. It is the expectation of temperament, size, coat and appearance that makes a purebred the pet of choice for many families. Some breeds come with inherent traits that some find unacceptable while others find the look appealing. Good breeders try to overcome health problems those traits may bring while still maintaining the look. No responsible breeder produces an animal such as the poorly bred crested that held the ugliest dog title for so long (which was bred by an ignorant breeder to continue his awful traits). All breeds AND mixed breeds have issues. Good breeders want their dogs to be healthy and take steps to eliminate as many health issues as they can from their lines, both by testing breeding stock and in choosing dogs to breed. They live with these dogs in their homes - they want them healthy and long lived. They suffer the heartbreak when one of their dogs pass on. Most breed, not to supply puppies, but when they want a puppy to continue their line, so there may be a long wait, but they may know someone else that is expecting puppies and might have something for you.
No one should buy a puppy without researching the breed and the dogs behind their puppy of choice. Don't be a window shopper buying on impulse. It isn't fair to you, the puppy or the breeder. All puppies are cute - but what will they grow up to be? What health issues might they have? Do they fit your lifestyle? Does the breeder have a good reputation? Not all breeders are created equal. Can you meet the puppy's parents? Have you seen the contract? A well-bred puppy has health testing behind him, has his shots, shows socialization and may not be available because there is a waiting list. While the breeder may want a certain pup to go to a show home, many prefer their puppies go to pet forever homes. Be prepared to have to answer many questions and have a home inspection. The hardest part of being a breeder is placing your puppies where you believe they will become permanent family members. In an age when partners who marry for love are often splitting up in hate, imagine that task.
Learn as much as you can about the breed first - it shows the breeder you are serious. Breeds have national club sites where you can go for information and they are usually listed on the www.akc.org They also have listings of rescue groups for that breed in the event you would prefer to help rehome a dog vs. a puppy. People who take older dogs often comment they will always take an older one instead of a pup in the future. It may amaze you how quickly some of these dogs come into your heart and adapt to your home. Many who have taken a rescue continue to come back for another as their dog passes.
There are those that tout their dogs, often of their own registry or one they paid to have entered into an open registry as problem free. They take no tests to prove it and often have no idea what caused a death. They cross breed and claim hybrid vigor. In the first place, hybrid vigor refers to cross bred animals such as a horse and a donkey, giving you a sterile mule. Every puppy carries genes from both parents and breeding a displastic mastiff to a husky with megasophagus does not give you a problem-free cross. Nor does breeding a golden with bad hips to a poodle with PRA and diabetes. Those genes pass on to the puppies. Genes behind those genes pass on. And those dogs at the shelter may also carry those genes. While dogs left to their own to breed and fail to thrive on their own through many generations may have strength through survival of the fittest, the claim that mixed breeds are healthier can only be made because no one knows or studies what problems they have or what caused their death. Purebreds are tested and kept track of. That doesn't mean not to adopt a shelter dog - just don't repeat the misinformation on the health or deem it a purebred because it has some common traits. You may get a long lived healthy dog either way. (Many breeders have a rescued mix breed at home) Not even dogs with parents who are clear of elbow OCD can be guaranteed not to develope it, you just have a better chance of having a cleared puppy. And a good breeder will guide you on how to feed and care for a puppy to prevent some problems that are not genetic.
As to inbreeding and line breeding, it is how breeds are developed. One does not take the poor puppies to include in their breeding programs. Dogs are tested for health issues and not included in close breeding unless the issue can be handled if bred to a clear dog. Those dogs are then tested and eliminated from breeding if they carry the unwanted trait. When the puppies begin to carry forth consistant traits, then one can set a standard and apply for registration. One can take an inbred dog out to an unrelated dog for traits they want to incorporate without losing the type they have set. For instance one breeder wishing to establish a tailless boxer without docking, bred to a tailless corgi and within 5 generations had dogs with none of the corgi trait except the lack of a tail that he was after. Once a breeder has established a line that is relatively free of health problems in that line, every out breeding can potentially bring new issues as well as strength. They must know their pedigrees and trust other breeders to be truthful. It is a science not undertaken without knowledge or possible problems...but those problems can show up with totally unrelated dogs as well. And all that testing is expensive. That's why not everyone does the testing, but who would you rather put your money down on?
Good breeders do not fill shelters. You are not killing a shelter dog if you buy from a breeder. The same people who came up with that slogan are helping to import dogs for sale in those shelters. (PETA has the highest kill rate of AR organizations) They are the reason for a boom in foreign breeders shipping to America as more and more hobby breeders get too old or feel the expense and hassle isn't worth it any more. (If wild, the Dandie Didmont would be endangered - many of the AKC breeds have very low breed counts) More people want dogs than are being euthanized in shelters (and many of those are not adoptable) The campaign to vilify breeders continues as PETA and animal rightists strive to end all breeding and pet ownership.
Breed clubs are the ones that set the standards and education on their breeds, not AKC. It is the breed club and its members that have to address health issues cause by extremes in their standards. People who like the wrinkles, head type and build of the English Bulldog need to find a breeder whose dogs can breath well and have minimal health problems with their skin. The breeder should cover all possible health issues for the breed, as it is a responsibility for the owner to keep the dog healthy. They should not buy such a dog and then decide it is too much trouble to put up with snoring, drooling and putting cream on their wrinkles. etc...they need to know that is part of owning such a dog. They must also take part of the responsibility of dogs that need c-sections to whelp puppies because they want that huge head and bully front. It is a popular breed for both its looks and its other features and if that is what people want, it is what they are going to buy. Their choice of breeder could influence future problems and high vet bills.
What has happened to some of the breeds is the responsibility of their breed clubs. While on one hand one breed may have ruined the hind end through fad (unfortunately not all breeders care more about the breed than "going one better" over what is currently winning), another breed now has very little coat problems, another has eliminated unique health issues through selective breeding, and so on. People who love their breeds become their caretakers and must be the ones to protect it. To not do so is to give credence to complaints about extremes that are not healthy for the breed. But just by virtue of being purebred, does not mean unhealthy or not natural. Many breeders work hard to keep their breeds in good stead. May you find them in your searches.