Hmmmm
Standard ME/CDL stuff. Allowing an aircraft to be flown with those provisions surely infers that the winglet is of real use, particularly in fuel savings. Maintenance costs, involving close inspections after every flight are not minimal, especially when time is precious down-route.
If we discounted every item covered in the MEL as not necessary for flight, there wouldn't be much left.
But thanks for the proof source DBate, which should help close this discussion. (Maybe!)