This is a common misconception. Phillips was not supposed to solve over torquing. It was designed to allow higher torques, stop slipping and self centre. It was only really good at self centering.
A screw designed to stop it being over toqured is a terrible idea. The screw should be smaller to prevent if higher torque is needed. If over torque is an issue then reducing the power to the driver is a much better solutio (easily done in industrial setting Phillips was designed for). You can also reduce the size of the screwdriver supplied.