Why not blind bake with two pie plates? 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?
I use two nested pie plates all the time when I'm blind baking a crust, but glass plates don't work well. Glass plates actually have a much bigger difference between their inner and outer profiles than you might expect, so I usually use metal pie plates instead of glass because they nest a lot tighter (the thinner sheet metal stamped on a die allows for much more precise nesting).

Just be sure to dock the crust, ensure there is no gap between your pie plates and the crust itself, and remove the inner plate a couple of minutes before removing the crust from the oven to allow any excess moisture to escape and brown properly.