Most players of an earlier era were introduced to the game through caddying. By watching and trying to copy the action of better players they developed their own swing. About the only "static" positions early golf professionals would teach were a proper grip and address posture. The lesson itself was demonstrated in one continuous motion emphasizing a steady head and fast moving arms and hands.
Not until new technology came along were instructors and players able to "freeze" the swing at various not before seen stages and positions. Soon players anxious to improve were pouring over books and magazines attempting to emulate the still positions of touring professionals.
Unfortunately these frozen images often did more damage than good. In an attempt to maneuver from position to position their swings became too thought conscious and deliberate. Their pre-occupation with positions and mechanics had sabotaged their natural swinging action. In other words they were mentally and physically getting in the way of their own swing.
You must realize nearly all touring professionals and top notch amateurs began the game in their youth. Through years of practice and play they learned to swing the club through the ball fast developing strong hands, arms and wrists in the process. Only later were they taught to use their body action to support the swinging element of the arms and hands.
Beginners and average players don't possess the strength and skills of players who began in their early youth. This is why after teaching a student the correct grip and address posture I emphasize the swinging of the club head. Only after a player has developed a free swing and sufficient club head speed will I introduce the proper body action and positions necessary to improve their control.
Some modern instructors feel the best method to teach beginners is studying still pictures so they can copy the various positions of tour player's swings. Although this may help a student learn the "ideal" positions it isn't going to do them much good if they can't hit the ball out of their shadow. Body action and positions are important in the golf swing, but they are secondary to the feel that is learned by swinging the club head.