While it may seem possible to detect quitters, the fact remains that there would be too much grey area to distinguish between people who intentionally quit or simply got disconnected for whatever reason. This is the very reason COD players who dashboard when they are host to completely shutdown a given match for the sake of preventing a loss (as well as griefing other players) NEVER resulted in a ban in the many years that COD has been out. It'a a headache they will not choose to deal with.