Who really knows though? If you strike anyone ANYWHERE hard enough it'll kill them. Perhaps you can generate the power to do this with a fist. That would take a lot of things falling in place, such as; your opponent being a complete tomato can, your opponent not knowing enough to keep good posture and defensive structure and, your opponent not doing anything to attack you in return (as you'll have to be fairly lucky to hit a shot in someone's throat when they are throwing back at you).

In short, it's not the easiest thing in the world to do. Not that it can't happen, only that it rarely does.