I don't think you gain much by forging this number on a single device and you wouldn't be able to manipulate this on ALL devices.

The reason the scam worked is that it encourages all readers to jump to the end of the book (via a link on the first page). I don't think there would be an equivalent way to force people to page through and pause on each page.

That may not make the scam totally impractical to all but the most dedicated hackers, but it does increase the scam costs substantially. Maybe enough to remove the low-hanging-fruit from the scammers and have them target elsewhere.

So, I don't think "that wouldn't change anything".