It means that you can install sysvinit or any sysvinit-compatible init, and all daemon packages still provide init scripts, as painful as that is. And Debian still supports installing systemd-shim instead of systemd, so you can have a desktop system with a non-systemd init and it'll still function.

> In practice it's not possible because of so many (unecessary) dependencies on systemd.

Such as? As far as I can tell, almost nothing depends on systemd. A handful of things depend on libpam-systemd (for session management), which functions with systemd-shim.

The amount of work that goes into Devuan for pulling out systemd of Debian Jessie is clear evidence that what you are saying is not easily possible.

As I understand it, much of that work goes into removing any trace of even innocuous things like libsystemd, which is used by applications that want to support systemd if available. All the necessary work to support a non-systemd init is already in Debian, making Devuan fairly pointless in practice.

That's correct. Debian ships sysvinit as well as systemd and daemons have initscripts/confs for both.

A lot of people still use sysvinit and it just works.

If this is really true, I might have to eat my own words.

Yes, it's true.

To replace PID 1 with sysvinit, run:

  apt-get install sysvinit-core systemd-sysv-
  reboot

To prevent it from coming back, create the file /etc/apt/preferences.d/no-systemd.pref containing:

  Package: systemd-sysv
  Pin: origin *
  Pin-Priority: -1

This works great on servers and lightweight desktops. As others have noted, if you want GNOME you also need to install systemd-shim. I have no experience with this, but I have no reason to doubt that it works.

If you do run into cases where something doesn't work as expected with sysvinit instead of systemd, please do file a bug.

For that matter, if this is a use case you care about, systemd-shim could use a maintainer or maintenance team: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=832508

I'm running openRC on all my systems and the problem is usually dependencies. As an example, both Brasero and K3b depends on something that depends on systemd. I can understand if a program uses the systemd library but these need systemd as pid 1 because reasons.