I don't think that's what they're arguing for. A system using systemd for managing which apps can run in the background can be managed by a task/tray-bar or wh

I don't think that's what they're arguing for. A system using systemd for managing which apps can run in the background can be managed by a task/tray-bar or whatever it's called, just as you expect it to. However, their lifecycle would be decided by yourself/the taskbar manager, rather than each application individually. So in theory, you could expect all applications to work the same, and any application could be minimized to the taskbar or be run at startup, without the program having to offer that functionality in itself.