Earlier quoted context omitted.
Apple did skeuomorphism really well, which is hard and requires a lot of design work. I cannot understand why they gradually abandoned that, as it was clearly a competitive moat in terms of usability. I've seen how computer illiterate or elderly people were able to navigate skeuomorphic designs with relative ease. Right now, they can't tell what is a button or a field and what isn't.
It was primarily because skeuomorphic UIs don't scale well with user experience levels. They're easier for novices but don't lend themselves well to expert use, unless you add a bunch of extra affordances that would seem really out of place in a UI meant to look like a real thing. And what does a skeuomorphic web browser or email app look ike? We don't have those in meatspace.
I disagree that skeuomorphic can't be used by power users. Just throw a bunch of keyboard shortcuts in there.