That said, ranger seems pretty slick for what it is.
Now, that 1:1 identity is broken. You can have multiple windows showing the content of the same directory. Also, you can have multiple icons on screen 'pointing' to the same file.
This may look like a minor change, but the feel of the UI is very different. It feels much less a direct manipulation interface.
Yes, Mac OS already was slightly inconsistent. Open and save dialogs could show directories and Windows that wer visible in the Finder. However, these felt as part of the application, and were very focused on the task at hand. Icons in those dialogs felt as representations of files, not as the files themselves. Also, there were aliases, but being files, they maintained the 1:1 correspondence between icons and files. Altogether, those things never killed that illusion of 'an icon _is_ a file, a window _is_ a directory'.
Because Mac OS X is a multi-user system, I think Mac OS X had to break this rule (network shares were already stretching the metaphor (almost) beyond breaking years before Mac OS X), but even today, it still feels like a loss to me.
My personal GUI progression was Mac OS 7.5, RiscOS 3, Windows 9x, Mac OS 8 & 9, BeOS, KDE, Mac OS 10.3, onwards. I didn't see a significant break, but maybe it's because of the detour. It just didn't occur to me that it was anything other than a smooth transition. By the looks of things, a good number of people seem to have noticed the change, and many don't like it. I'm not sure the 'classic' way of doing things was entirely compatible with a command line interface (I get that that's what Lisa and Mac was trying to supersede). But I don't think many doubt the utility of CLIs for 'serious' modern use. Do they?
One thing I do remember is that we've always had symlinks (aliases). I don't remember if they were in System 6 but they were certainly there in System 7.
[1] An oldie, but a goodie: http://arstechnica.com/apple/2003/04/finder