The reason is that there are tradeoffs. Fixing the timestep guarantees a frame of latency, but most (all?) integration methods used to simulate physics break down with wildly variable timesteps.<p>Tying simulation to framerate is often the best choice, when you consider that most hardware is average, it minimizes latency for the average user, and results with a more accurate simulation, so long as people keep vsync on (why do you need framerate greater than your monitor&#x27;s refresh rate anyway...).