Hypothetical proposition for reputable breeders...?

I'm no breeder, but how do you ume working dogs were created? People wanted a job done, you got the herding breeds. But is it possible to create an all friendly breed? Meh...well, all dogs need to go through the terrible Chewing and Puppy Stage, so no, not exactly. There will always be that predatory instinct, and what if a dog were to take after a squirrel with an elderly woman being towed behind? Not pretty. Technically, we already have something along the lines of a perfect dog, and that is a dog that has been trained as a guide, but no, not a breed.