Yeah, I noticed most of the top golf instructors were HOF Golfers. Wait a minute, now that I think about it, I can't name a single famous instructor that even played on the PGA Tour.
Once again, I firmly believe the vast majority of the professionals in any sport are Savants. You can't teach what they have since God gave it to them. Pretty hard for them to relate to Joe Sixpack and attempt to teach them at the level that is needed to be effective.
I think (not sure) there may be a notable exception. Perhaps a rising star who isn't that far from being ready to play professionally may benefit more from some teaching from the right professional.