Okay then, how about the following scenario which we often see:
(1) (Say) Battlemage Jaes is guarding.
He is hoping to attack the monster leader if it comes close enough but otherwise will hit another monster.
(2) The overlord knows this, so moves all his other monsters first.
(3) Jaes patiently waits to see if the monster leader moves.
(4) The Overlord decides it is better not to move the monster leader, unless he guard action has already been activated.
As everything else has been moved, he says "That's it. Your turn."
(5) Jaes says "Well, in that case I'll use my guard action to attack that (say) skeleton over there"
(6) Overlord say "if you do that, then I'm not finished and will move my leader monster after you do that"
(7) Jaes says "Then I wouldn't have attacked the skeleton"
Everyone then throws up their arms in frustration. Someone gives in, in the interest of keeping the game moving.