Most shifty types use the tach or engine sound to shift, but I suppose you have a point for those trying to jam gears with a thousand RPM difference.
It isn't just a matter of the driver's competence: unless the driver is double-declutching and blipping the accelerator (or in a clutchless case, just manipulating the accelerator to control motor speed), even with perfect timing the synchro rings still need to apply all of the torque required to change the input shaft speed. That's what synchro rings exist to do, but that's a lot more torque or for a much longer time with the motor attached and acting as a massive flywheel.
In an upshift, the input shaft needs to slow down - that takes (in a shifting time scale) approximately forever with a freewheeling electric motor, unless the shift fork forces the synchro to slow the motor down... a lot more work than the synchro is intended to do.
In a downshift, the input shaft needs to speed up - that will never happen with a freewheeling electric motor, so either the accelerator needs to be blipped or the shift fork must force the synchro to speed the motor up... vastly more work than the synchro is intended to do.
This is still all irrelevant to keep's Beetle if it is just left in one gear (likely second or third).