Oh but you DO have the manpower, what you don't have is the luxury to coordinate your entire life and others' to revolve around watching a base inside a video game. I like to look at DayZ with a realism pov, and if this were a real situation survivors would not have things like work, school, or other obligations to worry about, therefore allowing them to take turns on watch for a base. What people got to remember is that this is just a video game, players have lives outside of it. People don't log out in real life, disappearing from our world for the night. I believe leaving characters inside the game would be highly realistic, but there would still be no way of protecting yourself or your stuff when you're gone and would probably cause server problems. Having some sort of NPC counterpart to help you keep whats yours' is a much better option. I think the NPCs would add some realism to bases without forcing players to stay in game 24/7 and allowing casual players to have some sort of end game fun. I don't see how they would disrupt the core PvP aspects that you would see in the rest of the world as they wouldn't be roaming around all over the place, they'd be confined to only the bases and only there would be a small handful of them. If you walked up to someones' base that was being guarded by a real player, you would be met with the same interaction as from an NPC....bullets, lots of bullets. For anyone who really wants to get at your stuff, they would be just a small deterant, not some uber force that you have to launch a massive attack against.