Lu,
You said "The very purpose of a hydraulic servo is to not only resist feedback forces from the rotor but to be able to overcome any and all feedback forces."
1. In fact in many helicopters the hydraulic systems exist only because the AFCS needs it. In the case of the AS350 you can fly an AS350 hydraulics off but because of the loads from the starflex head you wouldn't want to for too long.
2. If you took a Model T Ford to the Indy 500 would is survive? Is that a design fault? Remember that whilst reasonable margins must exist (and are defined in FAR / JAR 27 and 29) they are there for a reason.