As an aircraft mechanic I claim with great self-appointed justice and knowledge that this is indeed a feature! :p
As long as the elevator control cables/rods aren't jamming the elevator control surface, or it is stuck in any other way, the trim-surfaces should provide enough force on the elevator control surface to move it aerodynamically.
Some modern designs have "servo control surfaces" that are there as a relief for the pilot to lessen the force needed to deflect the controls.
Whilst some aircraft designs use this as a primary control feature, the same operational parameters could indeed be applied to the aircraft trim-tab such as seen on the 110 or the adjustable tailplane on the 109. Disadvantage is that the control method isn't very responsive and will vary with airspeed.
By the way, the anti-servo tab works the opposite way of the servo-tab to provide MORE force on the stick so that an aircraft with very light controls won't be too unstable for the pilot.