Doesn't breed very often
When they do breed, don't always have puppies available to pet homes
May have a very long waiting list
Is overly "picky" about who they will sell a puppy to
Breeds more often
Usually has puppies available to pet homes
May have a shorter waiting list or no waiting list at all
Are not as "picky' as to who they sell a puppy to
In general it is easier and more convenient to buy a puppy from Breeder B. There are more Breeder B's than there are of Breeder A's . All puppies need homes, whether they came from breeder A or B. None of the puppies asked to be born. The notion that if people stopped buying from breeder B, breeders would stop breeding is a load of BS because people will never stop buying from them.
IMO, unless a puppy dies, a health guarantee is just a worthless piece of paper. Once that puppy is home it is family no matter what happens. Who returns a puppy like it's a handbag or a pair of shoes?
So, I guess it is just easier and more convenient to buy from Breeder B