Oh, don't get me wrong, I totally get the logic behind the rule. Marine LCcpls Jones, Ramirez, and Smith all see a Taliban dude with an RPG and each have clear shots, they are all going to fire at the same time. If Jones gets the shot off first, and kills the Taliban fighter, Ramirez and Smith still most likely wind up shooting to air or a dead body, and their rounds are wasted. Ramirez and Smith don't get to rewind time and shoot at another target.
That being said, this is very clunky, and with so many elements to keep track of, it seems really tough to keep track of.