It’s a bad analogy because there are different kinds of games, but only one kind of small talk? If you don’t think pub talk is a different game than a black tie dinner, well, you’ve obviously never played. Why do people do it? Well, when you beat a video game, you’ve beat a video game. When you win at social interaction, you’re winning at life—social dominance improves your chances of reproducing.
As for rule books: the fact that the ‘real’ rules are unwritten is part of the fun. Of course, that’s true for most video games. Pretty much any modern game’s real tactics come from players, not developers. You think you can win a single StarCraft match by reading the manual? Please.
I’ve never heard of this before, and Google suggests it seems to be mainly a component of NLP, with little supporting evidence. Still, I can’t find anything that puts paid to it either way, and it’s an interesting idea. Has anyone done a reputable study on it? Scholar yields nothing relevant.