Loss of power assist to the brakes and steering can be disconcerting in such a situation.
In older cars, you may turn the key too far and lock the steering wheel.
A lot of newer cars do not have locking steering wheels, though.
FFS, YOU DON'T INSTANTLY LOSE BRAKES AND STEERING WHEN YOU TURN OFF THE CAR. I bet that most of you posting that haven't actually turned off a moving car before.
You know what's even more "disconcerting"? Having your car suddenly lurch forward under full acceleration without a control input, and continue to accelerate as you try to control it. "My steering became a bit harder" is nothing by comparison.