Skeuomorphism was a design fad that most people moved on from fairly quickly.
Old macOS was barely skeuomorphic.
Here is what my Dock looks like right now, in Mavericks.
What real-world object is this supposed to resemble? I guess a shelf, maybe? How many frosted glass shelves do you have? Do you keep folders on the shelf? Do you keep them next to your trash can?
I bring up the Dock because I think it's the most skeumorphic element there is, if we're talking about the OS itself and not bundled applications. If we
do include applications—which, fair!—there was a two-year period during Lion and Mountain Lion when Apple added faux leather to Calendar, Contacts, etc, but it really wasn't a thing outside of those releases.
Here's the dictionary app in Mavericks. Notice how it looks nothing like a book:
And here's Calendar:
Skeumorphic design imitates the appearance of real-world objects. The Mac never really did that. It borrows
textures from the real world—frosted glass for the Dock, smooth metal for the tops of windows—but it applies them in unique ways that befit a digital object.
What old Mac OS did have, however, was
texture and
depth. The reason I'm using Mavericks right now is because, day to day, I just find the added contrast between windows, icons, and other parts of the OS to be much easier to process. Each window looks distinct and I can parse the screen more easily, even when it's full of junk from ten different apps I haven't gotten around to closing yet.
And this is also why I like Big Sur. It's still much flatter than I would like, but the stronger drop shadows go a long way towards making each window and menu stand out.