On Windows, if there has been value in putting those tasks in a GUI in the control panel, they will do it. It's the same deal.

Yes you can technically build a system without dbus or systemd or polkit or gettext or the C library or whatever it is you feel is superfluous. As you've found it is not actually difficult to do that, just tedious and impractical. You aren't gaining anything here by removing things. If you want equivalent functionality you're now tasked with building the equivalents, e.g. Android which is also a single user userspace for Linux without dbus or systemd, but has its own fairly complex set of high level services and IPC system.