Most problems people end up having with their horses comes from the owner/handler not knowing enough to be dealing with the horse, coupled with the "I don't want to make my horsey mad at me".
And it does not matter HOW kid safe a horse is, or how well trained. IF that horse picks up that the owner has no clue? Then you end up with a spoiled, resistant horse.
And your attitude as to you should be able to train your own horse, would be like you going to an Electricians Forum and telling those people that "everyone that lives in a house should be able to be able to wire their own house." See how far that gets you.
As for the whole "horse can't rear if moving forwards" thought? The problem with that is too often the rider can NOT get the horse to move forwards at all. And if you think that a horse only rears if it is "confused or conflicted"? Then you need to rethink that.
Horses rear quite often because they have learned it is a way to get out of doing something. Or because they want to test to see if it will get rider scared.
Also, repeatedly cantering horse in circles for a long time to "punish them" accomplishes nothing. Tires horse out for that time, but so what? Horses do not stand around and think "man, I had to run around in circles for 2 hours, I am not going to do that again" and resolve to do better next time.
Much of the problems you are having? Comes from your mindset of "I don't want to be forceful, I want my horsey to love me and be trained" which is wrong one to have. The rest come from your inexperience.
Horse has found out you don't have a clue. We have found out that you, like so many others, want to make excuses for horse and yourself, and want to argue with people who know more than you do about horses, their handling, and problems therein.
As FnB said? You have in no way solved anything, horse will just regroup. As for watching CA? I can think of no one worse to watch.
Horses make me a better person.