Bodyweighted striking means that you slam into the target with your entire mass in motion. If you slam into a heavy bag this way, it can make your teeth rattle if they are not held tightly enough. Making this observation, I had the following insight. It takes energy to make your teeth rattle. Therefore, if your teeth rattle, it is a source of energy loss. Therefore, if you hold your jaw tightly enough that your teeth don't rattle, that energy will not be lost. Where will it go then? Into the collision. Conversely, if the jaw is held more tightly than necessary, the excess tension will be draining the body's total store of energy. So even this minute and insignificant part of the body has a contribution to make in adding power to a strike. Likewise for every other muscle, joint, and nerve in the body.