I think you can find a good quality pup that does not come from an actual breeder. But for me that is different than a BYB. When I think of BYB I think of someone just pumping out pups for money. No regard for the health of the dogs. I think our english bulldog is from a BYB. He is actually a fairly healthy dog. But I feel like we good lucky. As a matter of fact, the first pup my boyfriend got (same breeder as our current dog) had horrible horrible airways and the dog choked to death on its kibble at 7 months of age.
Now, do I think this could have happened if he with through a reputable breeder, instead of a BYB that sold its pups to a puppy store? yes. But I think it would be less likely, and I think a reputable breeder would care more. Since the pet store sold him the dogs my boyfriend never actually got to meet the parents or speak with the breeder. There was no real health guarantee. For me it is obvious that the breeder was breeding for looks (the really pushed in nose is highly desired) but it is that really pushed in nose that leads to more breathing problems.
Sampson also has seizures and allergies. so I wouldnt say he is a totally healthy dog. But he isnt the worst bulldog I've ever met in regards to health.
They way i see it is there is always expectations to the rule. You can get an awesome dog from a BYB or breeder that sells there dogs on CL. You can also get a less than perfect dog from a reputable breeder. But for me it is all about risk aversion. There is some research that says drinking a glass of wine during you last trimester is not harmful. But do I want to take that risk? no.
And having a nice website does not make a breeder a reputable breeder. As someone else mentioned on here, it was after extensive research that I was able to better recognize the quality of a breeder. I still could have been wrong about some, but I think for the most part I could tell when the true interest of the breeder was in the dog/breed not the money.
Its not the testing itself that makes all the difference but for me its the fact that the breeders take the time and effort and they try to eliminate as many risks as possible. The breeder I got my dog from was showing me several pictures of his dogs, he sent me a picture of this gorgeous boy, I asked when he was breeding him. He told me that he wasnt breeding him ever because he has bad hips. That guy could have totally bred that dog and produced some really amazing looking dogs, but he didn't! For me that was a big deal.
I feel like buying a dog is a big deal, I only want to support those who really care about the dogs. I feel like if a breeder is a really good breeder then they dont need to post on CL or sites like that. Buts that just my opinion.