An important thing to keep in mind is that the centrifugal force on the blade itself will try to move it to fine (or low) pitch. Without external torque on the blade root, this will lead to overspeed - very quickly - as the prop behaves like a turbine, extracting its energy from the slipstream.
So the whole control mechanism - counterweights, hydraulics, cams, helical pistons, whatever - is always fighting this above physical reality.