Valve did this because they can afford to do so. They aren't giving the game itself to players, they are giving licenses to play the game. There is no physical distribution going on but rather digital. They lost no money doing this where as if Bungie were to give an extra copy of Halo to anyone who was affected by something similar would cost them thousands. This is why digital distribution is superior to physical distribution because shit like this is possible. Granted the company is willing to set aside the money factor. Which is why Valve is also superior to all other developers out there.