Based on this question, I got to thinking about alternative ways to blind bake, especially since I always have issues with butter crusts slumping. One thing which occurred to me is: why not use two matched, nesting glass pie plates? This would seem to provide maximum support to the crust, as it would exactly mirror the shape of the pie plate on the bottom.
I always thought that the reason why nobody does this is that the crust needs to vent moisture, so the weight on the inside needs some porousness. However, Stella Parks uses aluminum foil filled with sugar, which would have no ventability at all.
So, my question is: is there any reason not to use a nesting pie plate as the weight for blind baking? If so, what?