...and dogs not worth breeding do no good for the gene pool
Dogs not worth breeding may actually help the breeds gene pool, but may not help the gene pool that breeders like.
For some dogs that has proven true, though not in the way you're implying. More than one field trial dog has been sold off, done things the breeder didn't think it could, and then got bought back by the breeder for a great deal more than it sold for as a pup or got bred to one of the breeder's other dogs. That's not unheard of at all.
You're problem however comes when the dog is sold on a limited registration or with no papers at all and you
think your dog is something special but the breeder sees nothing in it they want.