Not to mention that in an emergency, you can always turn the key to kill the engine, and then put it back into pre-igntion (to unlock the steering column). You won't have power-assisted braking or power-steering, but with a bit of adrenaline-fueled strength, it is definitely preferable to being in a car that is stuck accelerating.
That's a lot of thought and action in a unexpected and very fast-moving situation. I don't think that's a realistic expectation, except perhaps for trained personnel like airplane pilots.
The service brakes of anything short of a supercar are sufficient to stop a car at WOT.