So much of what we think of as tailgating is what takes place before the game. Getting there early, drinking, grilling, playing games... No doubt that's the tailgating experience 90% of people have. But I've always thought the post game tailgate was underrated.
Think about it. What is the rush to get home after the game? Especially if the game was at 1p. When the game is over it's only about 4:15 or so. You probably haven't eaten since noonish. There's 70,000 people all trying to leave a parking lot with very few little routes out all at once. Why not fire back up the grill, let everyone else fight the traffic, and if you've got a TV you can just enjoy the first half of the 4p games.
In some ways a post game tailgate can even be better than the traditional pre-game ritual.