Why are they there in the first place? There's no way to seal the rotating gap between the drum and the backing plate, so gasketing the junction between the drum and the axle flange seems to be a fruitless effort!
I am not looking for an argument, and, I am no expert.
GM shows/lists those paper gaskets in the Master Parts Catalog: in Group 6.819 GASKET Wheel Hub (front & rear).
My understanding is that the "gasket" paper was/is used to help avoid "rust weld" of the drum and the backing plate.