Makes me think of Counter Strike. Its an adequate single-player time-killer, but it was meant for multiplayer. The single player was likely just meant to add a few more sales and to have something with which to kill time when you're not near a Wi-Fi port or generally lacking internet access. Also, they probably want you to keep playing as long as you can; adding seemingly-pointless single player facilities into an obviously multiplayer game achieves just that, even if its by a margin of a few extra hours.
At least, that's one of the reasons I would do it.