Actually, to be certain, electric motors decrease in torque and do not stay at 100% through the rpm range... they have an effective rpm limit and torque drops as it is approached. im at the edge of my understanding, but it’s basically tied to electromagnetic inductance - that it takes time for a coil of wire to build up and change the magnetic field, and once the rate (speed) of change needed is greater than the coils ability to shift, the power output drops. And conversely, if the coil accepts the pulse completely and saturates, it looks like a direct current short. Therefore there is a sweet spot, a pretty broad one albeit but still an operating window.
with Tesla’s and several others, this doesn’t show as an issue because there’s so much torque available from the massive motor and current capacity that gearing isnt needed. between the lines, it’s loosely stated in hybrid tech as one of the factors to where battery-only effectiveness is limited to an understood and designed-in speed transition to gas.