If I am an avid duck hunter I am not going to get an English Bulldog or an English Mastiff and teach it to retrieve the ducks I shoot with my shotgun. Sure I can teach a dog to retrieve at my demand. But I'd be better off in my opinion getting a gun dog. A bird dog or even a Golden Retriever might be better suited for the task. If I need a great dog for family and home protection I'm not going to employ Yorkie or Dachshund . I would expect a better breed to choose would be a Presa or Caucasian Ovcharka. I'm only naming a couple of breeds. Of course more breed will suitable as well. After selecting a more suitable breed then train the dogs to do what they were bred to do and respond to my cues to do it or stop doing it.
If I am an avid duck hunter I am not going to get an English Bulldog or an English Mastiff and teach it to retrieve the ducks I shoot with my shotgun.
Quite right EGP. We must select the breed based on the function they are to perform. Your example above is a good way to put things into perspective. Much the same as you would not want that English Mastiff if all you want is a lapdog.