You mean to pedal depowered ebike?
I pedal my throttle ebikes all the time along with motors and do not see any problems.
One of my ebikes EPLUS IS one of the most efficient ebikes you can find due to FOC + field weakening method of motor control and pedalling such ebike along with motor is a pleasure and excellent exercise.
I do not grind breaks a lot , I am on ELECTRIC vehicle. Especially when is wet.
It is all about how electronically ebreakes are implemented.