Equating mastery of an activity or area of knowledge with fitness to teach that activity or area of knowledge is a silly and often baseless assumption.
I had a professor in college who was a Nobel finalist - probably the smartest human being whom I've ever been around in my entire life. First day of class, we had people sitting in the aisles of a 180-seat lecture hall. But no one could understand a damn thing he tried to mumble to us (and he was a native English speaker). Five weeks later, at the start of class, there were 14 of us in the lecture hall. After 10 minutes, I was the seventh one to walk out of the class, since it was pointless to spend time in class straining to hear a genius who could not even explain adequately how to open the book to the correct chapter.
If expertise at playing golf must be commensurate with ability to teach golf successfully, how is it that we have any top-100 instuctors coaching PGA pros and giving others lessons? Surely if they have to be brilliant at playing to teach others, they would all be out making the leaderboards on the PGA, LPGA and Senior tours every week, making millions, instead of adjusting other people's grips and commenting on their hip rotations, no?