Snitch,
You've got an excellent point. And on that same line, a lot of the WWI fighters had externally rigged flying surfaces. You can see the horns in good photographs. Actually you can see the horns and the control wires as well. They were all "pull-pull" connections for all the surfaces.

On some of the aircraft, the horns were adjustable somewhat for tuning the individual airplane. And there is documentation that some airplanes were tuned for the pilot.

Some pictures include enough subject that you can see that some of the horns were designed such that there would be asymetrical movement of the surface because of the "off center" connection point for the horns. BTW, their connection geometry was exactly the same as our RC geometry. The difference was only that there were no servos, just a pilot's hands and feet.