I used to use flour under the pie and keep shaking the peel until I had made the pie and it was in the oven.
I found that when using a wet dough like I like to use, it made the bottom of the pie too floury and dry.
Using the parchment paper eliminates that and with the OO in the dough makes the crust brown nice and still be flexable. The paper will turn very brown and really you only need to leave it there long enough to firm up the bottom of the crust, and then you can slide the paper out from under the pie. I do my pies on a stone on an electric oven at 500f.