You do realize 2-handers HAVE won in international competition before and have done well for Team USA, right?
The object of the game is to roll the ball down the lane and knock down all 10 pins. There is no one way to do it right! I personally think that at least the two-handed delivery is much more effective way to magically gain tons of revs over the no-thumb one handed delivery. (It offers much more control at least) It is NOT the best method for all conditions, much the same as the one-handed high rev release is not the best method for all conditions, and the one-handed low rev release is not the best for all conditions.