This is very long answer that I will try my best to brief. Training with just positive reinforcement is incomplete training and can be dangerous in my opinion. I will discuss a few different situations as examples. In the case of a jumping dog, a positive only trainer would say train sit, train place, use a gate, keep the dog on leash as management all instead of correcting the dog for the act of jumping. These are not bad suggestions just incomplete suggestions. In the moment the cues of sit, and place can simply be overshadowed by the excitement or just pure interest of people coming in your doorway. Lets say your sit behavior was built of food.
Food has a maximum value at some point for dogs in this case lets say the value of food on a scale of 1-10 is an 8, but the interest your dog has in greeting your guest is a 10, what do you think will happen? you will say sit and your dog will go running and jumping towards your guest. Gates and leashes are fine, but restraining is not training. If we want to restrain why don’t we just keep our dogs in crates or in the basement? The end game that people want is for their dog to be loose, not jump and listen when given direction. In this scenario I would correct the dog as soon as they jump. This provides the dog instantly with information that says jumping on people is unpleasant.
It shouldn’t take more than 3 times for your dog to understand Jumping is not an option. At this point we can absolutely train towards keeping a dog in a sit or in place, but if you want to get rid of jumping you must correct the act of jumping.