God, it feels terrible to talk about people like this, but...
Selective breeding takes constant upkeeping. No matter how long a "breed" has been established there will always be offspring born with undesirable traits and without the desirable traits. In that case they are not allowed to breed while the desirables are. If this doesn't happen, the desirable traits will eventually become watered down.
I'm a dog person and I have Dobermans. The breed is relatively new by dog breeding standards , but still has been around 100 years. There are still Dobermans born too shy or too aggressive, or not the right angles, size etc. and these are generally spayed/neutered so they can't pass on their genes while the ones who meet the breed standard are actively bred.
That's why it takes a lot of knowledge to be a reputable breeder and some hilljack with two AKC dogs shouldn't start churning out litters