This shows neatly how some things are completely straight-forward in theory but turning them into a good, polished experience is the really hard and creative part (in this example: how to apply the effect in a split-screen game).
I think it's also a fantastic illustration of how even the best designed systems need to be twisted and coerced in some rather gruesome ways once they make contact with the end-user.
In order to craft a polished experience, they had to hard-code in a lot of kludgey exceptions to what would otherwise be a very clean simulation.