I have no problem with people training more than is necessary but to me that is not the point.
Correct me if I am wrong but one of the important premises of positive training is -
dogs do things best if they like doing them and I completely agree with that. My view is that much of the methodology of some positive training came about as they were teaching dogs to do things that do not come naturally, whether that is searching for drugs, explosives or dancing with humans! You are taking natural behaviours of the dog and altering them to suit your purpose, as no dog naturally wants to find small bags of cocaine hidden in a car, it has to be taught that it is looking for cocaine and that its handler wants it to find it! I would expect a young dog to be interested in the smell of a rabbit without me having to teach it to be.
Well bred gundogs should naturally want to hunt and retrieve and if you have to get a dog to do those things or worse look like they want to do them (chucking treats around to get a dog to look into very soft cover) through bribery with food then we are heading in the wrong direction. A collie could easily be taught to do simple retrieves, running from side to side around the handler and walking at heel etc. It should not be necessary to have to spend a long time teaching a dog to hunt or retrieve and going back to my earlier point, if they do it because the want to, they will do it better and more effectively than if they have needed to be taught to do it. They will instinctively know far more about hunting using wind etc than we can ever teach them and have more drive when the going gets tough.
As an example a small cocker who wants to retrieve will figure out for itself how to carry a pheasant better than a bigger dog who doesn't really want to carry it.
I use treat training and place boards early on to teach pups things that do not come naturally, because the methods work well but no spaniel pup should want to sit still or not run in after a retrieve. I don't want to have to do that for everything.
The danger is these highly trained but lack of natural ability dogs can win some trials on the right ground or tests and are regarded as good gundogs.
Great hunting dogs in my view are born and trained how to work with us using their ability, not taught how to do absolutely everything, if we have to teach them everything we will get more and more pups that need rabbit pens or huge amounts of game to get them interested in hunting.
The same trainer has this film
https://www.youtube.com/watch?v=Zsk4HW28kJw
At 4.38 she explains that the dog is on a long line as it "bogs off" if put under too much pressure. So according to this all methods of training put dogs under some pressure which I agree with. If this dog finally makes the grade would you want a pup out of it?! All working dogs have to be able to handle pressure whether that is sitting quietly when watching birds shot in a drive or stopping on the whistle having flushed a bird. Dogs who cannot handle pressure are extremely difficult to train and I would not want to have to give a dog treats to get it to give me eye contact.