> Because people don't buy CoD for the single player campaign they buy it for the multiplayer.
I assume 'people' means a majority. While I'm not privy to statistics specifically for CoD, one of the first games I worked on (Unreal Tournament 2004) was explicitly focused on multiplayer. It didn't even have a single-player campaign. You could play versus bots and that was about it. In spite of that, comparing sales with server data showed that only a small minority of our customers ever went online, let alone played predominantly online. I'd be surprised if CoD wasn't skewed even further in that direction considering its extensive single-player campaign.