Now let me see, shooting a skeleton over a graveyard fence would not be an issue simply because it happens to be a skeleton and if you are using an archer, it does not matter if there is a fence or not. If the creature on the other side is a caster it can cast back as freely as you can fire at it. Therefore as you say nobody is ,or was, likely to be banned.
Now the case of Andros is a little different, This is a new Boss and he is located in an existing dungeon. The placement of Andros makes it fairly obvious that the conflict is supposed to take place on the island which used to house the Ogre Lords. Here the terrain is not being used to gain an advantage, it is being used to establish total control. The players lure Andros in front of the ledge on which they place their pet archers and then go and have dinner if they wish while their pets kill Andros because Andros is locked in front of the ledge with no method of fighting back and simply stands there till he dies. The players can then collect their drops, rinse, repeat, with no risk whatsoever. It is certain that this has been overlooked when it comes to this Boss encounter and as far as I can see is much more of an exploit than the balls, at least there the players still had to do something.