If the Buddha were all-powerful then there would be no wars, famine or suffering in the world like there are today. If the Buddha were all-powerful then he would certainly not allow for these things to happen and he would certainly have rescued us all from cyclic existence. That we still wander in cyclic existence and that these problems endure is proof that the Buddha is all-knowing but not all-powerful. He has provided us with the path for overcoming samsara but whether we pursue the path and practice it rests with us.
Depicted from "Guide to the Four Preliminary Practices 3 - Part 14" April, 2015, Vancouver, Canada