small example
Schleicher Ka 13 gliders have original manufacturer figures for cockpit loading, calculated to allow the wing to fly efficiently as a sailplane.
Structural calculations show that a higher AUW is safe, but it becomes a toboggan, descending at higher airspeed and sink rate...
So there is a difference between BGA dispensation loadings, and design loads....
If/when the elevator or linkage fails, who carries the can....the manufacturer has clearly stated the design loads.
I took a Ka13 to a reputable workshop, and assisted in the C of A work.
Subsequently it was sold as salvage, due to rot in the wing spar near the airbrake box.
The accident didn't happen that time....
Demonstrated loadings may exceed calculated loads, and vice versa....