True - but here's something to investigate.. can you control the engine thrust with dead batteries?
As far as I know, most modern FADEC controlled engine types will keep running if main, standby, and emerg busses are lost. Engine driven pumps keep the fuel coming - spar valves are motor driven, therefore not held open electrically. The FADECs are powered by engine-driven dedicated generators.
The only glitches would be in icing conditions since the igniters would be unpowered and also full thrust situations where the engine driven pumps may not be able to keep up with the demand.