Basically it is the wrong way in which the golf swing has been analysed and consequently the teaching this is based on is equally wrong.
Incorrect teaching can never lead to progress and achievement.
Nearly every golf instruction book, even by some of the great players, have fallen down and have often done more harm than good. If you look at all major sports in the world it is clear there has been process of analysis with a consequence that standards have been raised based on a true theory of improvement. Look at the level of achievement in Olympic and World track and field records over recent years. The increase in performance levels are the result of improved teaching based upon the correct study. For any real progress to be made in golf teaching a start must be made from a correct analysis of the basic swing movement.