Suppose you don't care as much about replays, and you're willing to use other tricks to "cheat" on multiplayer sync instead (because most AAA titles seem to have multiplayer these days). Suppose, instead, your top priority is visual fidelity and being perceived as having cutting-edge graphics. You want maximum computational effort going into letting the gamers with a top-of-the-line GPU render on their 360FPS monitor. And you want lots of objects and realistic physics.

If you run physics on a global timer, you could run it at a slower rate and try to fake some of those frames (extrapolating intermediate positions of objects), which is complex. Or you could run it at a faster rate, and every frame has real physics updates, and then it's taking time you could be using for graphics or something else that you think sells better. And there are ways around that, too, but they're complicated and your team is busy and they aren't what your engine gives you for free...