“applicable to all the multi-engine/rotor “contraptions” that are popping out as fast as weeds grow. Reliability is directly proportional to complexity / parts count.”
You’re joking, right?
There are tens of thousands of parts in a turbine engine, and thousands of parts in a piston engine. Electric motors have maybe 100 at most. Even if an urban air mobility aircraft has 10 motors, even if they all tilt, it will still have fewer parts than a single piston engine.