There is nothing wrong with correcting a GSD with a prong collar for reactivity or dog aggression, if the correction is applied properly. However, this method is completely wrong, useless and counterproductive:
"Anyway the dog is reactive to other dogs. He growled and barked at another close by dog and the girl severely yanked the dog down by the prong collar and literally smothered the dog. He was crying and squealing terribly. She held him down for about a minute all the while the dog was just screaming. "
Alpha rolls have gone the way of the Dodo bird. Holding a dog down is just poor handling, an obviously ineffective technique and a good way to get bit in the face. This is a good example of exactly what not to do. If the trainers did not step in and stop the idiotic stuff the handler did, well you need to find better trainers. I would have stepped in, taken the leash and walked away with the dog. I then would have walked the dog right by the dog he barked at. As a trainer I often take the leash and show the handler how to handle their dog. Demonstrating the correct way to handle dogs is big part of dog training. Explaining things only go so far, IMO. When I take someone dog and show them how easy it is to handle dog aggression or reactivity, it goes a long way to making a point.
If that happened a half dozen times during your class, obviously this technique wasn't working. Again, after the first time the trainer should have stepped in and made a point to the class. The point would be, this is exactly what you do not do. If the trainer is afraid to take this dog's leash and demonstrate how to handle the dog, find a new trainer.
One dimensional trainers that can only work with clickers and treats are about as useful as trainers that only only know how to yank and crank a dog. The style may work with easy dogs, but more challenging dogs need a more balanced approach. As a trainer, if your afraid of dogs or getting bit by dogs, you need a new profession. You need to be able to step in and correct the handler and the dog simultaneously. Both need a stern correction for their poor behavior. If one of the K-9 handlers in my unit did this, I would give them a harsher correction than I would give the dog.
There is nothing wrong with making a dog aggressive dog yelp from a correction, that is kinda the point. To stop the behavior immediately, instantly and ensure it doesn't happen again.
I agree with your point that this handler needs one on one help and to be taught how to properly handle, train and own a dog. After a correction, praise and reward bus the offered at a higher level than the correction.
I'm not sure I understand this:
I just don't understand why GSD owners seem to think that extreme punishment with the prong is necessary with these dogs. Rottys, Dobes, Mals and other big dogs all seem to get this harsh treatment out of course.
I own a GSD that is tougher and harder than most Rotty's, Dobes and Malinois I have seen. I do not see why one would think the dog's breed determines what type of correction it gets or can handle. Corrections are based on the individual dog's temperament, hardness and behavior. While my GSD, Boomer is a fairly hard dog he rarely needs needs corrections. When he does, it is effective and over quickly. My Malinois / Dutch Shepherd handles corrections entirely differently. He is a somewhat handler sensitive dog, highly reactive to prong corrections and very hard when in drive. Two dogs that need to be handled and worked differently. A prong works perfectly with the GSD; and will get you a dog working his way up the leash with the Mal X Dutch Shepherd.
“Beware of false knowledge; it is more dangerous than ignorance”. George Bernard Shaw