There's so many inputs that it's difficult to casually come up with an intuition-guided estimate. So it makes some sense to have faith in the empirically guided value. We hope that they took the time to validate their algorithm for extrapolating the energy consumption.
The trinsicoin algorithm is really just a minimum bound based on the most efficient rigs known for a given algorithm and the cheapest industrial rates for electricity. The Litecoin Foundation actually helped out with some of the math and data resources.
