It also didn't always work. At no point did the MacBook boot nearly as instantly as an iPad. That said, Jobs' obsession with UX was a powerful driving force and your point stands.
Probably both. Apple Silicon macbooks seem to never actually sleep, they just switch to the energy efficient cores, similar to how iPhones / iPads never truly sleep either. You can tell by leaving e.g. a while loop in zsh running and printing the date + sleep, and when you reopen the lid you'll see quite a few iterations actually completed.