We do use the ground for both winding up and unwinding. What I think you're referring to is straightening out the front leg. In general this is contrary to what we do. This move essentially helps generate speed having the arms/club pass the body at impact. They're sending the energy "up" so they can swing their arms through against the body vs. how we rotate and trap the ball using the body and arms unwinding. Moral of the story... if you try this move, your distances will be very inconsistent, and the ball will be all over the place unless you have exceptional talent and can consistently square the club face... and then you still can't trust it. You also may hurt your front knee if your front foot is flatfooted and you turn through fast . One other thing, many top players have different swings for different shots. You usually see this "up" move with Driver or a very long or hard-hit shot.
Move Less ... Get Good! DUPLESSISGOLF