Reitlehrers (and a reitmeister) says he did things with horses that they would have tossed away, that is praise.
Is he for everyone? No. Are there things to be discussed as to why? Or what the differences are? For sure.
Would he have had any impact 30 years ago? No, because all horses were ridden up/open/and towards lightness in hand/self carriage. That is a big difference.
Equally equitation stood before all other things, it is prerequisite to being able to train.
It's rather like the riders (german/french) which changed horses after an olympic (in 36). The german said 'for me there is no difference', and the frenchman said your is more obedient. That speaks to the nature of the people doing the training, the exacting vs the lightness.