Pure hypothetical - A plane requires -2% elevator (push) to hold straight and level inverted flight. Set the elevator hysteresis loop to a total height of plus and minus 1% each side of zero. Now trim the elevator down -1% and go fly. For straight and level flight, pull very slightly and then release - the hysteresis loop of +1% offsets the down trim of -1% and the plane holds straight and level. Now roll 180, push slightly, and then release. The hysteresis loop of -1% adds to -1% down trim for a total of -2% to give hands off straight and level inverted flight.

I'm not proposing this and I would not fly this set up, but it is the only scenario I can imagine where hysteresis might be hypothetically useful. As a practical matter, I would think having non-centering servos would be a real pain in the backside.

Bob