But this conjecture predicts that Steam prices will drop immediately to their final low price. So Steam is actually also a counterexample.
E.g., it is implied that consumers can postpone their purchase longer than the monopolist is willing to realize the profit. Is it the case here?
Or is there actually a game so durable that is not losing its appeal over time?
And is there a game which can be considered a monopoly (as an activity for spending free time)?
All of these points have to be fulfilled, none of them is, i.e., the conjecture simply doesn't apply.