Well, you definitely have a valid point. I think the message is: "consistency." I think that is what we can expect when we get dogs from reputable breeders. That said, I have two rescue dogs and two breeder dogs. I love them all the same and I may favor my rescued dogs because of the hardships they endured prior to living with me, but the truth is, I can only trust my breeder dogs with, say, little children, etc. because I know the rescued dogs have unknown histories and dislike children and can behave very unpredictably.
All these dogs are worthy of love and we need to rescue and need to keep breeding, but we need to have realistic expectations either way.