To our modern eye, these horses appear to lack muscle and roundness over their frames, and yet the old movies of their performance will display amazing self-carriage, activity behind and lightness in the hand. As she readily admits, what she has discovered works for her, but may not be the route to Rome for every horse and rider. Following the discussion since that article has been intriguing, but also sort of amusing, since I think everybody could be right, depending on the situation and the horse. When I started taking serious dressage lessons, I never remember being given a recipe to ride every horse a certain way. That concept may mean a slightly different thing for each horse, and that's where the trainer has to make the right call.
Horses come in different shapes, temperaments and abilities, just like people.
What works for one animal does not necessarily do the trick for another. Since the days of the old masters, our perception of what is correct has evolved to the very high caliber of performance the top riders of today are expected to produce. Thanks to improved breeding methods, he is also a better machine, built for the job.