Kind of amazing that the terms “front end” or “back end” (or even the concepts?) don’t even occur in all this layer unpacking. Author seems to stop at “your team’s code running on your server”. Well, some of that code will be running on clients, and nowadays it’s unlikely to be your server that hosts any of it, because clouds. So there’s considerably further to go in either direction, even without increasing the zoom level.
I don’t mean this as a put-down: it seems to be a thoughtful essay, and all such explorations must stop somewhere. Just incomplete in a way I found surprising.