Automated control of aircraft has been with us for decades; having designed flight safety critical systems, I am astounded that this particular subsystem was not comparing both AOA sensors. In a 'disagree' situation, the system should simply raise an alarm (MCAS offline?) so the aircrew know something dodgy is going on.
It should be inconceivable that a subsystem capable of changing the control surfaces is not redundant.
That said, as the crew did not even know of MCAS, they might get confused with "What the hell is MCAS?"
To me, this is a fundamental design flaw that should never have got past the independent technical authority even within Boeing, let alone by the FAA designated representative.
The flight control system on the 777 is a triple redundant system, incidentally (with different processors in each lane at that).