Well the Cap is based on players it is the way it is designed, Zero point players normally end up that way once the have lost there last city. They then have the option to "restart" they have about two weeks to restart before they lose the place on the server.
I also imagine when the player Cap was calculated it was taken in to account how many players would be at Zero while working out the workload.
It has always been this way as long as I have been playing.