There is certainly the phenomenal especially in dressage of a conscientious rider getting to a certain level where the short cuts come home to roost and they start having riding induced physical issues in the horse as well as behaviorial.ones. if the rider is conscientious they may switch trainers and try new strategies. If not, they can euthanize or retire and start all over again.
Usually folks get into this predicament because they don’t have much knowledge in biomechanics or ground work or body work or hoof angles etc. So while they are advanced riders, they are newbies at this other sphere of horsemanship. Hence potentially vulnerable to snake oil salesmen who pretend to be intelligent and qualified. Also likely they have been up to now traveling on the expert and credentialed side of vets and trainers and farriers, and perhaps not questioning any of the Best Advice, so unaware of the depths of incompetence and fraud on the outskirts of horse world.
But very often also having no need to think critically about the Best Advice they are getting from their accredited and mainstream horse team. No one questions vet advice on rehabbing pulled tendons, or farrier advice on bar shoes or pads, or trainer saying ride forward into contact, don’t let him get away with that, etc. You are paying well qualified professionals to make your decisions. You may not even have control over your horses feed in a quality barn. So you don’t have a need to think critically until it’s too late.