so should they ban all coaching in other sports?
Once players are out on the footie field managers watch from the green room? No time outs? No boxing coaching in between rounds?
You are looking at this from the wrong perspective.
Imagine inventing a sport, your thoughts are not going to be :-
player A vs player B, but they can ask for help / advice part way through the game is it?
Coaching should be to prepare you for a game.