The Benefits of Clearing Gold Reserves

Why can't you have a bank or a depository issue a digital currency backed by its gold reserves and then have people transacting in that? Why not even just do what a company like gold money does and allow people to digitally transfer ownership of gold instantly anywhere in the world for free. If I can do that instantaneously using an app on my cell phone I mean why bother with bitcoin I don't get it, he says.