Am I misunderstanding what you mean by saves? That seems pretty important to me.
At times this wouldn't work and I would lose my progress, but I'm willing to attribute that to the fact that it was supposed to be a rare case backup mechanism, rather than the necessary crutch it is currently.
I made my statement based upon my experiences playing. For one, I played the game for 3 hours disconnected from the servers - I knew my progress wouldn't be saved but I just wanted to play. It seemed to work fine aside from region play and that my progress wasn't saved.
Another time I lost my internet connection for 15 minutes. I continued to play. When I got it back, it claimed it re-sync'd my game with the server. As a test I logged out and back in and it all looked the same.
Maybe there is some simulation on the server side. But it doesn't seem necessary based upon my experiences playing the game.