Jimbo: I know you are not going to change your mind. But you only have one part of the story, the part of the amateur self-taught but you are missing, ignoring and despising the professional side. If you think that one person with no formal training can reach the same result as a professional with many years of formal education in music, you are in a big, big mistake. You can't realize it because of your lack of training (sorry, I'm not meant to sound rude) and this gap is preventing you from widening your vision.
If you take a look to the history of piano technique, you'll understand that cannot be reduced to the simplistic question "what came first". Modern technique is the result of many decades of investigation, instrument evolution, trial-error, knowledge sharing between colleges, hundreds of books and inheritance and perfectioning of piano schools from teacher to teacher. This evolution involves some great teachers and some great geniuses. It's just impossible and illogical that one individual will reach the result of this only by him/herself. Please, don't trivialize the Art of Piano. If Medicine and Engineering requires years of study to inherit the knowledge and findings of the former generations, Music isn't in a lower step.
And been a professional doesn't mean automatically been the best possible, it just mean bean professional no more no less. An amateur pianist with no teachers (I'm not talking about a pop keyboardist as Janny) is doomed to acquire bad habits, bad technique, lack of self-hearing and even bad music interpretation because of the lack of knowing what can be reached, what must be reached and, most important, how can be reached. My experience listening (and some times correcting real horrors and vices as a teacher) self-taught amateurs demonstrates this. I 'm still waiting to listen a self-taught pianist who reaches half the level of a professional. I listened no one until now. If this exists, please let us know.
Topic: Is It Possible to be an Expert?