Is indeed fun, and a great tactic, but not an "intended" strategy for the game. Besides, everything they've done to the Heavy ammo in crucible doesn't prevent anyone from being able to steal the opposing team's.. In the hands of skilled players, almost everything is deadly, and going back to day one would be like intentionally nuking the planet because, "-blam!- it." The game would fall apart, and things would be exactly the way they've already been up to this point.