Well, I'll challenge the idea that Parelli won't work with every horse
lol. Parelli will work with every horse. Parelli will not work with every person. It will work for every horse because it's based on HORSE psychology and how horses play with each other and based on dominance games they play with each other. Parelli will not work with every person because some people have huge egos and don't want to let it go, they are closed minded, they are afraid of change, they don't want to admit they are wrong because it's so much easier to label and blame the horse, they are afraid of other people's opinions, and a bunch more reasons that I will choose not to post. Some people just flat out don't care enough about the horse and his opinions and thoughts.
My warmblood is a huge example of how Parelli works even with horses with extreme behavioral problems. This horse came to me a labeled biter, kicker, man hater, was said to be dangerous, vicious and unpredictable, would charge at you when in his stall, would rear when asked to canter under saddle, would bite and strike when given a shot....the list goes on. He intimidated everyone at the barn. He was going to be scheduled to be put down if he hadn't found a home soon.
Seven months later I'm riding this horse bareback with just a halter out in a corn field, playing at liberty with him in the pasture, cantering him in the field on a completely loose rein, he will come from a canter to a walk and then back up without reins....the list goes on. Shots are now a mild issue. He does not bite or strike and it's over and done with quickly.
So (folds arms, lol) I still stand by my opinion that Parelli will work for ANY horse, but it WON'T work for every person, unfortunately.