I think it's where one plugs the external world into in their brain. For my daily work, I plug the desktop to my current thought stream (or short term memory?). Anything not immediately relevant to what I'm thinking about is an unnecessary speed bump or stutter in my speech, which means minimal window decoration, no status bars, ... and anything not visible can be summoned by a quick single "label" somehow, not by navigating a structure. This is more similar to what the author suggested.

{And if I'm getting what you said correctly} What you described, is similar to how I organize my drawers in my room. Everything is visible at once, but navigating them usually takes 2 or 3 steps. Without this visual map I'm completely lost.