Sometimes my internet connection knocks me off the server and I quickly log back on. I am not arguing that my internet service sucks, because it does. However, I am often in a warzone and when I am kicked off and log back in I am no longer in that warzone. All my progress is lost.
Many other mmo games have it so that you have a grace time of at least a couple minutes where you can log back on and still be in the warzone, or whatever instance. That way, any progress isn't lost if you can log back on right after you have been knocked off.