I’ll buy that. And the truth is that all sport is constantly evolving. It has to or it will die. The essence of what is correct remains the same, yet the stuff that goes around that essence is constantly evolving & modernizing. Look at human sports at the elite levels. The athletes have gotten bigger, stronger, and more technical over the years as the the fields of sports medicine/conditioning & nutrition have advanced. I remember very politely sitting though a video of figure skater Sonja Henie my aunt brought once. I’m one who can see & appreciate the effort of an athlete even if I’m not familiar with the sport. Watching poor Sonja I quickly found myself thinking, “omg, is she actually going to do something!?!” The technical standards of figure skating have changed so much over the years. Even comparing Torval & Dean’s performances to modern pairs there is a huge difference.
I think dressage is similar. Watching the video of Dr. Klimke & Ahlerich it occurred to me that while the tenants of good dressage vs bad have not changed, there is much more emphasis on the flow in & out of movements nowadays. I realize the video was spliced, of course. I think you still get enough of the moments entering & exiting the movements to see. The top riders now are riding every stride. Whereas the top riders in the past were imo more relaxed about what came in between the movements & weren’t consciously riding every stride to the max.
I don’t think either way is right or wrong. I do think it is a natural evolution of the sport as we get further removed from the days of cavalry training. No horse or rider could’ve ridden every stride back then, nor would it have been expected or actually desirable.