Thanksgiving is a time for special, seasonal, Thanksgiving-specific foods. When else, except maybe at Christmas, do you roast a turkey, bake stuffing and make cranberry sauce? Never. And it's the rarity of Thanksgiving dishes, the fact that we make them but once a year, that makes them taste so wonderful.
Apple pie is not a special, seasonal, Thanksgiving-specific food. Apples are available all year round, and you can buy a Sara Lee apple pie at 3 a.m. in the middle of April if you want. Why dilute your harvest feast of unique dishes with something commonplace?
But apples are at their best in fall! you counter. Nice try. Apple season is in September and October, not the end of November.
Apple pie is usually double-crusted: There's one crust underneath the filling and another crust domed on top. The top crust is superfluous under normal circumstances, but it's complete madness at Thanksgiving. People eat a lot at Thanksgiving, and they tend to be full of turkey and stuffing by the time dessert rolls around. They do not have room in their bodies for extraneous crust. Pie crust is like fatty, starchy concrete. It lodges itself in your intestinal tract and stays there sludgily for days and days. Thanksgiving pies should deliver a flavorful filling to you as efficiently as possible - that is, with just enough crust to keep the thing from falling apart.
Everyone knows that apple pie is nothing without vanilla ice cream on top of it. But who serves ice cream at Thanksgiving? Lunatics, that's who. Thanksgiving desserts must always be garnished with whipped cream, and whipped cream on top of apple pie is simply laughable.
What pies do taste good with whipped cream on top of them? Pecan pie and pumpkin pie. Conveniently, these pies are also Thanksgiving-specific, single-crusted, and made from New World ingredients. They are the only pies that should ever appear as part of a Thanksgiving spread.
So please, if you outsource dessert duties this year, make it very clear that you will not accept any pies that are do not contain either pumpkin or pecan. Thankfully, though, if someone does show up with an apple pie, you'll have a deep hole in the backyard ready for it.