Furthermore, anticipation is a key part of the Thanksgiving Day emotional arc. Two p.m. is underdeveloped, premature—a mealtime selected by someone who has not yet learned to delay gratification. And besides, what does one do after wrapping up the meal at three or four? A nap, yes. Leftovers, yes. But that leaves a Hunter S. Thompson–esque haze of unfilled time in which overstuffed, possibly tipsy diners wander without purpose, probably asking one another overly nosy questions, counting down the minutes till bedtime.
What of an evening mealtime? Dining at, say, 7 p.m., while standard on a regular night, precludes one from experiencing the vital activities that follow a feast: a genuine nap and ample time to digest before reheating a plate of leftovers later in the evening. Just as practically, if guests traveled any significant distance and are not staying the night, a late dinnertime means an even later return home.
Eating at 4 p.m. tidily resolves these concerns. A leisurely meal would then end at 5:30 or so, which is still plenty early in the day for an hour-long nap and a return to leftovers, in the form of a pre-bed snack, at 8:30 or nine.