> macOS gave up on the absolutely brilliant if misunderstood Mac OS X green + a.k.a "zoom"

It’s still there. Window > Zoom from the menu bar, or ⌥ + click the green window button.

It's almost like window management is primarily being used for facilitating inter-app interactions, rather than intra-app interactions... almost like tabs were invented for a reason...

Did people lose the old art, or have you never managed to grasp the "new" one?

I really wish mobile browsers had windows (true windows that could be switched easily, not the weird crap where you go into a submenu to find the list of windows and try to figure out which one has your tab, and Firefox doesn't even have that). I would love to split up my browsing into multiple workspaces on my large tablet, but instead I get to have four browsers installed.

I think a big reason it's lost to time is because it was poorly-specified and therefore a non-portable art.

E.g., there's no way for you to easily send me the desktop state of the open window sizes and dimensions you have in mind. And even then, I'd have to hack the window decorations and fonts myself. I'm back to meth-addled chicken pecking!