I would argue that, “Singularitarians believe that the world is “knowable” and thus computationally controllable.” A simulation doesn’t have benefit unless it provides insights for improved methods of controlling or managing the system.
This also rests on the premise that everything is measurable processes within our brains, similar to how bits work in a computer. But there is a possibility that part of the process takes place outside of our brains, as some form of tassid knowledge sharing or even collective consciousness (I realize this is somewhat controversial in a scientific context, but it’s an idea worth exploring at least as a hypothesis). If that is true, then trying to replicate a world, simply by observing the individual human brain, would be similar to trying to figure out how a radio works, without realizing that it receives audio through an antenna, or observing how a computer works without realizing it’s connected to the cloud.
Chaotic systems, such as the weather, are, by definition, sensitive to initial conditions and, therefore, are unable to be simulated for anything but short periods of time.