Chaos: The frequency of utilizing a rule is not a reasonable measure of whether the rule should exist. In chess, the 50 move rule is rarely used (as a percentage of games played), and the en passant rule is also rarely utilized. The stalemate rule may come up even less frequently but is a factor that cannot be ignored in tactical considerations. The 50-move draw rule would serve tactical purposes too in Espionage, i.e. "sh*t or get off the pot."