This absolutely is not true. Most trainers that show competitive horses in about any event will do most of their training while mounted. We do this because we can. Our horses are respectful because we don't take crap and are 100% consistent. We do not need to teach very much on the ground because we ride well enough to get the point across quickly to the horse. If I teach a horse to properly yield to leg pressure and rein pressure, he will side-pass, disengage hind quarters and move his shoulder over the very first time I ask. He will do this with less than a week of riding. We do not need to do it on the ground because our timing and feel and proficiency at using 'pressure and release' are good enough that we do not need to. It is kind of like round pens -- round pens are for people -- not necessary for training horses.
We have seen this big craze in doing ground work because we now have dozens of the clinicians that have found it more lucrative to train people than to train horses. They are trying to work with people that are somewhere between novices to inept and completely incompetent beginners with little or no experience and little or no natural aptitude or ability. They have found a way to keep them safer -- they just keep them on the ground until, hopefully, they learn a little more about the nature and responses to expect from a horse and can, hopefully, get a little respect out of 'Poopsie' before she kills them. Some of these beginners never get on their horses and you find the PP disciples that never get past the ground games or the CA disciples that never get past the constant flexing. All of this is to keep the neophytes safer and keep them from ruining as many horses. Meanwhile, trainers that can actually ride well AND teach and train horses, are riding their horses and are light years beyond needing a lot of ground games and exercises and round pens.
Personally, I want a horse to move lightly and quietly every single time my body language and/or a soft smooch asks him to. It takes me about an hour to get what I want from a green horse that is partially gentle when I start him. Then, I teach them to longe (without a round pen) and I ground drive every horse I start. I am really 'picky' how they are longed and driven.
After that, I am able to teach everything I want them to know from their backs. They are all respectful and they all step over or back without ever tightening the lead-rope. They all side-pass and they open and close gates with one week or less of riding. They cross creeks and ride out in rough ground (by themselves) with less that 1 week of riding. I cannot think of anything that more ground work would improve.
Maybe rephrased to "In order to do anything undersaddle, you should be able to do it on the ground", though...
I don't understand why you're hating on everyone who takes advice from a trainer like Clinton. He's a respectable horsemen. I know a lot of trainers that use his groundwork methods and they work great. Heck, I use them and they work for me! *I'm definitely no professional, I probably fall more into the novice kid range*
Just remember that we can't all be professionals, and if there were no beginners and novice horsepeople, then the horse world would die, and the trainers would make no money!
Don't get me wrong, I'm positive you're way more of a horseperson than me (I'm a teenager for Heaven's sake). I just really don't think it's a good way to go about training for the average person.
Sorry for so off topic, I'm just going to stop posting on this thread now.