The S-76 servos are not in the "correct" place for simple unmixed controls to be used. We have a mixer on the top deck to take roll control (for example) and split it out to the two servos that must tilt the swashplate properly to affect a pure roll.
The servos would have been in the perfect place, but we decided to put in 17 degrees of delta 3 in the rotorhead after we had designed the main gearbox casting. To redesign the casting would have delayed the program (the boxes were already being poured) so we just fixed the angle with the mixer on the upper deck.
It is interesting to hear all the reasons given here, from all the sources. This explains why Lu is so often misdirected. For many esoteric pieces of aerodynamic and programatic trivia, the answers are not found by calling someone at the "factory" or elsewhere!