You see students change their approach to a stall due to the relative movement of the ground 3,000 ft below? And when the student is most likely looking ahead anyway?
All I can say is this is not my experience. At 3,000 ft the movement of a distant horizon is barely perceptible. If your students are getting frequent wing drops during stalling exercises the cause is not keeping the ball in the middle, not the wind.
Aircraft do of course weathercock into wind on the ground. Not at altitude.