My Apple ARM laptop has 24+ hours battery lifetime in practice, three times as much as the best laptop I had in the 2000-2015 period, and it's lighter than most of those laptops too. (Can't remember the battery lifetime of my 2015-2019 laptop.) Clearly not all efficiency gains have been eaten up.

Agreed, it's not a perfect linear line, but if we how 2000-2015 computing requirements _and_ the Apple ARM efficiency we could be somewhere very special.