Are there lookback rules in youth levels of baseball? I never really understood why the rule is there at all. Defense/pitchers should be able to "take care of" baserunners without needing some unevenly-enforced rule....
To get the runners to commit and keep the game moving, otherwise the runner could just stand off the base, unlike baseball, the runners must be on the base before the pitch begins, they cannot leave early, but if we don't force them to go back to the base there cannot be any leaving early.
The point of the rule is to keep the game moving. They need to return so the game can continue. If the pitcher is not making a move they are saying they are ready to pitch so the runner needs to get to a base.