The one thing Mac OS X got right in 2001 was consistency and predictability. When you learned how the UI worked in one app, it was almost guaranteed to behave the same in other apps.
Now today, we have this mess of Catalyst apps, SwiftUI apps, old Cocoa apps, and even worse, Electron apps.
Scroll speed and behaviour is inconsistent across all of them.
Drag-and-drop support, once a hallmark of the Mac UI, is spotty at best.
Even basic stuff breaks every once in a while. It's wild to consider that Apple literally wrote the book[1] on how to provide a consistent experience for an entire OS, and yet they don't seem to be able to follow it themselves anymore.
[1]: http://interface.free.fr/Archives/Apple_HIGuidelines.pdf