Sports&#x2F;games rules are inherently arbitrary. This is like asking why you can move while dribbling but not while just holding the ball in basketball. There is no why. There only is.<p>Can you move while tossing the ball in the air repeatedly (dribbling against the sky)?<p>No.<p>Wait why? It&#x27;s just like dribbling except upside down.<p>It&#x27;s just the rule.<p>It&#x27;s just the rule, man. The rules are what define the game. Why can&#x27;t I start the bishop where the queen is? It&#x27;s just the rule. Why can&#x27;t I have an under inflated ball? Just the rule. Why can&#x27;t I use a cricket bat in soccer? Just the rule.