God of War III says no to loading screens

With God of War III confirmed to not require a hard-drive installation and the game being on a dual-layer blu-ray, we expected the game to have a bit of load-time issues. I, at least, expected it to relate a bit to Uncharted 2‘s load times. Well, apparently, there won’t be any loading screens, at all.
“And since people asked,” Christer Ericson, Director of Technology at Santa Monica Studios, said on Twitter, “God of War III has seamless loading. No install, followed by 10+ hours of play uninterrupted by load screens!”
The only question that remains is: how are the minds at Santa Monica able to do this but smaller games like BioShock 2 or Borderlands (for example) still require a mandatory installation?