The init-functions hook shipped by systemd translates calls like
"/etc/init.d/foo start" into "systemctl start foo.service".

This was added as a convenience feature for users during the transition
to systemd, so the system would behave more sensibly.
Users that were used to call init scripts directly could continue to do
so without getting weird results (like a second instance being started
not under the supervision of systemd).

The cleaner way obviously is, that packages remove their SysV init
script when they ship a systemd service file. So there would be no
confusion and an init script could not be called by accident.

Packages nowadays often use more advanced features of systemd, like
instances, where a simple translation/mapping between the sysv init
script and the systemd service file(s) is no longer really possible.

I thus wondered, whether this lsb hook should be dropped?

Or, given that sysv init scripts are no longer supported, a better idea
might be to replace the hook script with a simpe

if [ -d /run/systemd/system ] ; then
	echo useful error message
	exit 1
fi

This would send a clear signal to users that calling sysv init scripts
no longer work / is no longer supported nowadays.

Thoughts?