You're proposing nothing but hypotheticals based on what a utility SHOULD care about as opposed to what they ACTUALLY do. And it's an exhausting amount of mental gymnastics.

As for my father's invention, the reason it didn't catch on was for the same reason that piles of rocks don't actually scale -- it's incredibly inefficient, as is every other rock-based thermal storage. Just because it's a functional method of accomplishing a task, doesn't mean it's the best method, and what you've repeatedly asserted is that YOUR idea should be the best method simply because you say so.