[Raph_Koster]

Remember, it's about prediction (point 1 of the 12). Pure random cannot be predicted. From a prediction point of view, it is therefore ironically, an already determined result. So it is solved, and therefore not interesting.

In Theory of Fun, I phrased this as "everything has patterns, but if you are not equipped to see the pattern, it becomes noise, and therefore boring."

But it's the same underlying point.