So morally, if this game allowed you to accidentally drop something on the ground without you noticing it (I know, obscure example, but follow me.) and it allowed other players to see that item and pick it up, would you stand exactly where the item dropped and then constantly seek out the owner of the item? Morally, you should, but then what stops a unmoral person from stepping up and claiming the item.
And then, after you give this person the item, he/she walks away of course, the real owner walks toward you and says, "Okay, wheres my loot?" of course at this point, you basically stole their item off the ground and gave it to someone else. Who is in the wrong in this crazy world of ours!?!?!