Let me state the obvious: biological muscles are amazing. Their low inertia, their quiet operation, and - which is what we focus on here - they have a high peak torque at low speed and a high peak speed.
Electric motors are amazing too. You can get much higher power/weight and they can maintain large torque as you go to higher speeds.
The peak power of an actuator is basically the largest square you can fit under the torque(speed)
power = torque * speed
So you could emulate a muscle with motorB which has the same peak power. But then you would end up with much less peak torque at standstill and much less peak speed.
To match peak torque and peak speed of the muscle, we have to choose a motor with a much higher peak power.
Mona reaches human peak torque and peak speed performance and hence her total power is a stag
Note: The torque-speed curves can be shifted by gearing and we chose the gearing of Mona such that the curves intersect the peak torque and peak speed points of human muscles.