Grip, posture, alignment etc are not the fundamentals of a golf swing, they are
variables that you can tweak to suit your specific style of play. If you look at the Tour pros they all have different things going on in their swings; some stand more upright than others, some use a weaker grip, some may set up closed to the target whilst others are open. They can't be swing fundamentals if they are different.
The golf swing is supposed to achieve 3 things:
Rule 1) Hit the ball.
We need to have a swing that enables us to hit the golf ball, as often as possible, in the right place. There is no point having a swing that throws you off balance or causes you to hit the ground behind the ball, or on top of the ball. What we are looking for is something that is consistent and repeatable - that's it! Why complicate it further?
Rule 2) Hit it an appropriate distance.
Every golfer wants to hit the ball as far as possible, in doing so many sacrifice Rule No1 (hit the ball). Taking a run-up will work if it's distance that you are after! What you need to do is establish a swing that enables you to hit the ball the best distance possible without causing you to start duffing shots or throw yourself off balance. A good set-up, posture and (to a degree) your physical condition will help you to gain more distance. Sometimes better equipment can actually help.
Rule 3) Hit it in the right direction.
If you can hit the ball consistently and far enough then you need to learn to control it. If you can consistently hit a 230yd slice with your driver time after time than that's great! You're probably doing better than you think. You are achieving Rule 1 (hit the ball) and Rule 2 (distance) all you need to do now is learn what controls the flight of the ball and how ajustments in things like grip/alignment/clubface/weight shift/posture/ball position etc can influence the flight of the ball.
Most amateur golfers can't fulfill Rule 1. They sway about a lot, get off balance and do not consistently get the club to where it needs to be at impact. Even if they are meticulous in their grip/posture/alignment etc they still can't actually hit the ball with any regularity
It's a hard enough game if you ARE in balance, it must be a nightmare if you move about a lot and try to strip the skin off every ball you hit
