right now it's possible to trick unaware players into a potential loss.
You can send a friend request to the opponents of your friend and when they accept it, you can watch them and tell your friend about his opponents' dofus position and cards in hand.
That's why you shouldn't accept strangers' friend requests while in a match, but there are definitely some unaware players falling for it.
To protect them, you should only be able to accept friend requests while not playing a match. There's no real need to accept requests as fast as possible, so the "delay" won't harm anyone but may save some player's from being cheated.