they are worried about cheaters, and mainly because of the people who will cry about the cheaters lol
they make multiple accounts and send resourses or attack to gain resourses so they can build up faster trying to be the best, and how that would be fun i have no idea, they miss out on the actuall game play but they also start killing the game off because people dont like to play with cheaters
then you also have the players that didnt like the way their city was going so they made a new account and left their other city that cant be conquered and wont dissapear so i can have the land to make a new city lol
if someone dont log into a city for a month then the city should be auto removed, i say a month because people go on 2-3 week vacations from time to time
but this seems to be a fairly new game still so there are a lot of things they will need to do for quite a while and probably plan on doing and im sure they'll figure a way around everything, just takes time

