Oh - I wasn’t saying it was right.
I’ve just seen enough rearers from heavy hands and blocking riding that it could be that the “prepared” solution was to make the horse more afraid of the whip than it was of going forward into a heavy hand and blocking legs.
I remember when I was in my early 20s, I exercise rode for a few people who took lessons from the same trainer I did. One of the horses started objecting to his rider’s ride after I rode him. I was puzzled, and the trainer told me that I could not ride the horses as I would ride them if I were going to exercise the horses, I had to ride them the same way as their owner rode them. Their owner was very handsy. The trainer explained that by giving the horse a nicer ride, I was making them less tolerant of the poor ride that their owner was providing. It made me very uncomfortable, but the philosophy was that it was easier to change the horse than it was to change the rider.
I stopped riding for that trainer shortly thereafter, but it was a lesson that got burned into my brain.