The quote was on a message board comparing the different systems of learning how to have a better seat and be a more effective rider. The poster commented something to the effect that most instructors teach riding in a way that has worked for them and works for most of their students. Some systems work better for the over analyzer, some for the visual person, and some for the artistic intuitive learner. As the student riders advance in each of these systems, let's say Mary Wanless, Centered Riding, or Enlightened Equitation, they start to look and ride more and more like each other until you have serious overlapp in all of the systems and a beautiful, effective rider. Hmmmmm, something to think about. The base might look slightly different, but closer to the peak of really good riding most riders look very similar.
I have yet to find one system that I can do by myself, learning through books and video that has been stand alone to improve my bio-mechanics. However, combining things from a few key sources, has really been the ticket for me. A little bit of projecting the waist to the hands from Sylvia Loch, combined with the following/not following seat of Heather Moffet, and add a dash of dressage theory from Beth Baumert has really worked well for me. Even to the point of running into a specific problem, looking at all my most trusted sources and trying each different way of using my bio-mechanics. Oddly enough, most of the time it is just slight variations in the "how to" that have led to success. Because we all learn and process information differently, a slight variation can lead to great things.