I think you are missing the parent's point. By "kernel up" I think they mean that the kernel can stand alone without any other software. It's not very useful,

I think you are missing the parent's point. By "kernel up" I think they mean that the kernel can stand alone without any other software. It's not very useful, but it does work. Then you add system executables (sh, ls, etc.) and the only thing they require is the kernel (and maybe each other). You keep adding more and more layers, each depending on the previous but not the next. The top of the stack is, as you say, what the user wants/needs and it is dependent on all of the previous layers. The current situation with systemd is that this hierarchy is no longer valid and low level components are now relying on things above them in the stack. So much so that, for example, if the web browser stops working you have to reboot the computer because it hung a kernel process somewhere. That doesn't seem like a very good system to me.