In reality this is a training system that is not that difficult to learn. In it's most basic form it's a method of communication that is very very clear for the dog. Dogs learn the marker language quickly and when they do they thrive in the training. The marker system produces dogs that love to train.
I had been training dogs for almost 45 years when I started to learn this system. I felt like a kid in a candy store when I saw how well it worked and the attitude of my dogs that were being trained with markers. The fact is I still feel like that when I see dogs work with markers.