Yes and no. If you are making your crust from scratch, then yes you do need to blind bake the crust. I spoke with the experts at King Arthur Flour, and they explained that the cold quiche filling insulates the pastry and prevents the bottom crust from cooking fast enough to set up before the butter melts. This makes the butter melt out of the pastry causing the bottom crust to get soggy and greasy. More on that below. Moreover, the upper edge of the crust will not bake before the egg custard sets up and will be pale and wan. But when using frozen pie shells, it is not necessary to blind bake the crust. I have tested this recipe both with blind baking the frozen pie shell and straight from the freezer and both work well. I spoke with the baking experts at Wholly Wholesome and they agreed that it is not necessary to blind bake a frozen shell. If you do decide to blind bake your frozen pie shell, make sure to use a pie shield to keep the upper crust from getting burnt.