Unlike you guys, I think Djokovic knows what he's talking about. It's just that others might be too stupid to understand.
Kinda like if a Zen master told you a truth, would you know? The gap is like that between DJ and us mortals.
As to why I think Djo is correct about wrist snapping. The action is correct as long as you don't injure yourself and it adds power. If you train everyday to reach your best potentials, wouldn't you want to extract every ounce of power out of your mechanics? The wrist is one of the moving joints so it sure can help with acceleration.