There is an analogy here: the visual6502 simulator just simulates transistors, with an adequate but imprecise model. It loads a description of a chip - presently the 6502 - and then acts out the behaviour of that chip. Other 6502 models out there were written by understanding how the CPU works - we only had to understand how transistors work. Michael Steil's presentation at 27C3 includes a graph claiming orders of magnitude less work for the same fidelity.

To upload a mind into a computer without having to understand how minds and brains work, one might similarly model at the neuron level and then upload a description of the neuron characteristics and connectivity.