Why must the spectators be silent when a golfer is performing? In every other sport cheering is part of the game.

Seems like pretentious claptrap to me.  Passing the football to a running receiver takes skill. Dodging the opposing players and sinking a basketball takes skill. Both of these are done with all sorts of activity and distraction.  Yet golfers must kneel and eye their shot with grave concentration.  Then stand over the ball and shift their feet and hips a few times. Look at the ball, look at the hole, the ball, the hole.  Then take a few quarter swings.  Rubbish! Other sports take their shot while in action with crowds trying to distract them and the opposed player trying to prevent the shot. 

It takes lots of skill and concentration to play golf. It's a difficult, thinking game. This is the reason you have to be still and quiet when someone takes a shot.