Should Food Stamps be allowed to pay for Fast Food? Several states allow this...why does the Fed gov allow it?

I have always understood that food stamps do not pay for foods that are ready to eat when bought.  Papa Murphy's was smart to not bake their pizza's; they build them send them home with you to bake on a provided platter in your own oven.  Food stamps are honored.   I believe the restriction is warranted and common sense.