Mike:
I think your concept is completely believable. I have never met one, but I can believe that there have been, are, and will be artists who have a real natural affinity for color, value and hue and can "do" without someone training them. I believe them to be few and far between.
But that ain't me! For me, art is hard. I have to learn in order to do, and I have to do and do and do in order to do with any proficiency at all.