
Whether badly bred dogs are KC reg, mickey mouse reg or unregistered they still exist and people still breed, buy and own them.
Good breeders do the right thing, they don't need to be forced to health test etc. It is up to potential owners to educate themselves as to which health tests are appropriate and assure themselves of the kind of temperament of the parent stock.
The main issue temperament wise with UK dobes was that they had become soft, but that is exactly what the majority of puppy buyers want, as most dogs of any breed are required to be pets.
Personally my view in modern UK society in our crowded Island, there really is not room for dogs of the guarding dog breeds, to have this trait at a highly developed degree.
Such dogs should be bred and kept only by the armed forces, Police etc and should never be allowed in the hands of the general population.
It scares me that there are people deliberately importing foreign breeds with very heightened guarding/fighting/protective instincts. Many were bred to do their job in remote regions and not expected to be social.
Breeds with other traits like hunting, herding and retrieving are lass problematic as they can be safely managed.
My own breed has a strong hunting instinct, and it can be a pain that recall is more problematic to train, and more care needs to be taken if you wish to allow them off lead. ditto many terriers etc.
Thankfully these traits are unlikely to make them a dangerous liability to own in amateur hands.
There are other breeds with high work drives that make them poor candidates as pets unless they are with an owner who can give them more of an outlet than a daily walk, which is what most pet dos will get if lucky.