Anything that happened during the game would be much more hazy in terms of "history" and would not have affected the single player games as much.
It would also allow this game to continue for 10 years without breaking lore. People have asked the question "What happens when the in-game time runs up to the Reman Era? Or the Third Era?"
Assuming that there is an in-game clock/calendar, a dragon break would prevent them from leaving the interregnum (or other time specified time period).
Thoughts?