If you've lived in your house/apartment for a good long while and settled in, you have an idea of what it was like to use Classic Mac OS 9 (and earlier).
It's like flicking a lightswitch or reaching into a drawer and grabbing a spoon without looking. Everything is always right where you left it. Double-click a folder and the window opens in exactly the same state that you left it when it was last closed. All the icons are arranged in the same way, with the same label colours you gave them, and each of the folders inside that folder open the same way as well. One folder might open in list view sorted by Date Modified while another opens in icon view with the exact arrangement you decided on, all according to the way you left them.
All of those folders open their windows in the exact same position, size, and shape they had when you closed them. This lets you quickly drill down through layers of nested folders, moving your mouse to the next one before your eyes can even register it on screen.
The effect of this extreme level of persistence is that you develop muscle memory for the mouse. No other operating system environment I have ever used works like this, or at least this pervasively (modern macOS still has this for the menu bar). Everyone else just gives up and relegates the muscle-memory control to the keyboard only. This is a huge tragedy! A Classic Mac OS power user works with one hand on the mouse, one hand on the keyboard, and uses muscle memory with both to fly around the UI and work very efficiently. This is especially valuable when you're working in software that needs the mouse anyway, such as art or design software.
There was a lot of research leading up to 1980's-1990's UI design showing that people have a good understanding of physical persistence and the ability to remember where stuff is. This is why you can walk to your favorite restaurant or find your car after parking it.
Most modern UIs actively break spatial locality, so they don't work well for human users.
Imagine a parking lot that continuously shuffles the locations of all the cars, but you have a clicker that can make your car's alarm go off. You can walk towards it, and, although it might move while you're headed towards it, it is generally moving slower than you, so eventually you can find it.
This is kind of how Amazon warehouses work, and has the advantage that it can scale to infinite inventories and load balance access patterns really well (especially for robot pick + placers).
It also famously burns out human workers.
Note that the article spends a long time complaining about spotlight bugs. This is because there's no way to find anything on a modern version of MacOS. Logical directories (like Applications, Downloads, Documents and Desktop) are split into multiple physical unix directories. Photos aren't even stored in a directory at all!
The transition from OS9/Win 3.x to OSX/modern Windows is like moving from the house you grew up in to squatting in a never ending series of shopping malls and being forced to move on every few hours or so.
It's like flicking a lightswitch or reaching into a drawer and grabbing a spoon without looking. Everything is always right where you left it. Double-click a folder and the window opens in exactly the same state that you left it when it was last closed. All the icons are arranged in the same way, with the same label colours you gave them, and each of the folders inside that folder open the same way as well. One folder might open in list view sorted by Date Modified while another opens in icon view with the exact arrangement you decided on, all according to the way you left them.
All of those folders open their windows in the exact same position, size, and shape they had when you closed them. This lets you quickly drill down through layers of nested folders, moving your mouse to the next one before your eyes can even register it on screen.
The effect of this extreme level of persistence is that you develop muscle memory for the mouse. No other operating system environment I have ever used works like this, or at least this pervasively (modern macOS still has this for the menu bar). Everyone else just gives up and relegates the muscle-memory control to the keyboard only. This is a huge tragedy! A Classic Mac OS power user works with one hand on the mouse, one hand on the keyboard, and uses muscle memory with both to fly around the UI and work very efficiently. This is especially valuable when you're working in software that needs the mouse anyway, such as art or design software.