When looking at the affects of finishing high I looked at other sports. Watch bowlers as they release the ball. They release the ball with their hand on an upward movement to give the ball spin holding the finish high. Softball pitchers release the ball with their hand moving upward holding the finish high to give the ball the spin they want.
Top spin on a golf ball promotes true roll. True roll aids in speed control or distance control. Hitting down on a golf ball causes back spin while hitting up on a golf ball creates top spin. Considering ever action has an inverse reaction, if the back stroke is low and slow it encourages a forward stroke that accelerates and finishes high.