You spend your hard time playing PoE, Crucible, or some heroic strikes and you get a good or god roll on a gun you always wanted. You head to your inventory to infuse it with a weapon you no longer use... but wait, "Didn't I just use this gun to infuse? Why is it still in my inventory?" Then you realize the gun you meant to use to infuse was locked and another god roll weapon you had unlocked is missing from your inventory. Only you can prevent despair, lock your weapons.