My hypothesis is today's "modern" OS user interfaces are objectively worse from a usability perspective, obfuscating key functionality behind layers of confusing menus.
It reminds me of these "OS popularity since the 70s" time lapse views:
https://youtube.com/watch?v=cTKhqtll5cQ
The dominance of Windows is crazy, even today, Mac desktops and laptops are comparatively niche
I did like some Windows things, though, like the ribbon, and reconfigurable UIs. Today's UIs are more immutable, for the worse.
The problem is that way too many people approach macOS with the Windows way of doing things firmly planted in their minds as “correct”, which interferes with this process. For example, over the years I’ve encountered numerous posters complaining about how macOS can’t do X thing, after which I point out that X thing is right there as an easy to find top level menu item, but the poster in question never bothered to take a look around and just assumed the functionality didn’t exist since it wasn’t surfaced the same way as under Windows or KDE or whatever they were coming from.
Of course there are things macOS just doesn’t do, but there’s plenty that it does if users are willing to set their preconceptions aside for a moment.
MacOS seems to _require_ some unergonomic combination of both from the get go. Some basic things are easy with the keyboard but hard/impossible with the mouse and vice versa. The Finder app doesn't even have a button to go 'up' a directory for god's sake.
For the case of the up button for example, prior to OS X the Finder was a spacial file manager where each folder had a single corresponding window that remembered its position on screen, allowing users to rely on spacial memory to quickly navigate filesystems. Its windows didn’t even have toolbars, because they weren’t navigator windows — every time you opened a folder you got a new window (unless that folder’s window was already open, in which case it was foregrounded).
So when OS X rolls around in ~2000 and switches the Finder to navigator windows, they’re looking at what existing users will find familiar. Back/forward is easy since most had used a web browser by that point and map cleanly to most people’s mental models (“I want to go back”), but up? That’s a lot more rare. A handful of folks who’d used an FTP client might’ve been familiar with the concept, but few outside of that few would’ve, and how “up” relates to a filesystem is not in any way obvious. And so, the Finder never got an up button, just a key shortcut because anybody advanced enough to be hunting down shortcuts is going to understand the notion of “up” in a filesystem.