User blog comment:Jimeee/Elder Scrolls Online will be subscription based/@comment-74.216.41.165-20130918014841/@comment-16047389-20130919151955

Regular games aren't as massive or frequently updated as MMO's are. Imagine of CoD or Battlefield had map sizes of Skyrim, and could hold tens of thousands of people in the same game at a time. Then, every few months, they add 50 new weapons, a new area, and maybe a new game mode. That would be the rough equivalent of an MMO. You will not get that kind of support and activity in games that you only pay for once.