Actually, the best set of game rules typically do include mechanics specifically to handle the case of one player going completely off the walls and screwing things up. This is where we get things like chess clocks, red/yellow cards in sports games, "mercy kill" rules, etc. Even the bankruptcy rules in Monopoly are written a way that technically prevents a player from giving away all their property rather that giving it to the owner of the hotel they just landed on. It's harder for an RPG, but it is possible to build in provisions that prevent...
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I never know how to feel when this thread accidentally slides into legitimate game design discussions.