I must be one of those oppinionated people you were refering to
Not all people who "follow" Parelli are good examples of what the program is really about. I know some people around here who I can't stand. I would never let them lay a hand on my horse for that matter. One of them offered me to play with their "level 3 horse" and I couldn't believe how spooky and unconfident this horse was. But these people are extremenists and they take things way out of context. But that's not the program's fault.
On the other end of the scale, you have people who are naturally more soft and nice and lovey so they have a hard time being firm with a horse. Contrary to what some people believe, yes, we are firm with horses in Parelli when needed.

I have a friend who is this way and I have been helping her with her horse, and really they are not a good match for her to be learning on. Her horse is very dominant and can be snotty where she has a harder time being firm with him. But she is a dedicated student of the program and these past 2 weeks have been amazing for her. Her horse is listening to her now, he doesn't argue nearly as much and she is even trail riding him now. But because she is dedicated and was willing to search for the answers she has made huge break throughs.
Parelli is just as much a human training program as it is a horse training program. Who do we have to become in order for our horses to trust us completely, to want to be with us and be the most amazing partners we could dream of? And really, the first 3 Levels of the program are really about the human, not the horse. Sure, you are teaching your horse along the way, but it's more about finding "that" inside of you in order for it to work. I think that's why some people don't like Parelli......they don't want to look inside themselves and admit that they are the ones causing the problems. They don't want to change or they aren't open minded.
For me, I have had to learn how to be more patient, understanding, and soft. I was really good at being firm with horses, I'd smack or jerk on them if they were bad, all that stuff. Parelli has helped me find that balance of love, language, and leadership, as they say. I have amazing success with horses now, be it my own or friend's horses.
My new horse who I've had for 3 months now was going to be put down if he hadn't found a home. He was said to be a biter, a kicker, a man hater and a dangerous and aggressive horse. He was a 16.2 hh bully. So I decided I wanted him

Turns out he was just scared most of the time, he was extremely defensive and would brace up against steady pressure and try to bite. Sometimes aggressiveness can come across as "bad" behavior but if you look at the whole horse it CAN be fear. His motto was "I'll get you before you get me." He's been through some really bad stuff in his life and he didn't think people were a very good thing.
3 months later he is a completely changed horse. Actually, the TRUE horse finally has revealed himself to me and he is a blast to play with. He's finally confident to ask me questions and to have a conversation with me instead of going introverted and catatonic while learning something new. Through Parelli it's shown me that he is unconfident as a learner. This will get better as time goes by.
Basically why I wrote all that is because if you dedicate yourself to learning and understanding this program just like you would dedicate yourself to your chosen discipline then you will have amazing success. I would not have had this kind of success with my new horse if I hadn't been using Parelli. It's way more than wiggling a rope......it's a way to be with a horse, to understand them and to think like they do. One of Pat's mentors (I believe it was Troy Henry but I'm not positive) once said to him, "If I could put an ounce of human into the horse and a gallon of horse into a human, then we would truly have an amazing thing." See, it's really not about changing the horse, it's about changing us.