A bit of headline fail there:
"Introducing Surface Book 2, the most powerful Surface Book ever"
Out of the two of them so far?
"Introducing Surface Book 2, the most powerful Surface Book ever"
Out of the two of them so far?
Improvements along a particular dimension aren't always a given. If they said "Introducing the Apple iPhone 8 Plus, the lightest iPhone ever" they'd be lying. You can't assume that a newer model of something is always going to be more powerful.
Language isn't purely literal. Especially when there's a limited number of words to market to people. You can't write a 10 000 essay. So mentioning a detail isn't just to communicate the literal facts, it's to highlight details, point out significant details. So when someone says "it's the most X ever" they are saying that the improvements are significant enough to make them notable.
In EU there's a law that forbids using such an unsubstantiated/unverifiable/subjective claim in the advertisements.
EDIT: Recalled one more detail: If you use a claim like that in the commercial then EU regulatory institutions can demand an actual peer reviewed research paper backing it up :)