This is all very simple.
Some folks can really teach golf. Some can't.
Anyone, and I mean ANYONE, can read any of a thousand golf books, and "make a hacker a better hacker."
Also, any method that uses a KNOWN WORKING GOLF SWING as a model, and gets the student to do 90% of that model, will produce results ranging from so-so, all the way to the "almost tour level."
Then we have the stone cold truth that you could have ALL YOUR FACTS WRONG, and still help a tour player win, and maybe even win big, even if your "wrong facts" + your teaching ability - the students interpretation = better D-Plane production, and (or) better contact.
For the 10000th time, here is my definition of what a really good teacher is:
A great golf teacher can help any student play better golf.
With almost any student, a great golf teacher can start getting measurable positive results early in their first lesson with a student. And they can make these measurable gains while utilizing orthodox procedures.
When they are faced with a student that doesn't respond to "normal" measures, they can invent new ones on the fly.
They can teach little kids of any age, They can teach older folks. They can teach world-class athletes, or non-athletes.
When you watch them teach live, they are as impressive compared to a "rank and file" teacher as a Ryder Cupper is compared to a club pro hitting balls, or short game shots.
When their information improves, their teaching does. But they can make sub-standard information "work" to its maximum.
They can teach teachers to teach better, and can adapt their teaching to any learning style.
Understanding how people learn, if you just haven't been blessed with the gift of teaching ability, is a very important "learn."
A teacher that fit the above criteria would almost never explain any concept "exactly" to any student.
Most of the time, the less the student knows—within reason—the better.
But, if you teach someone something that is not quite scientifically correct, or maybe even junk science, you'd be better off saying less.
Or nothing.