Comment 9 for bug 1532198

Richard Laager (rlaager) wrote :

The spl package creates /etc/hostid in order to guarantee a stable hostid. Retaining that may be important, because if the hostid changes, pools will not import without being forced (which is not something that should be encouraged). Moving the contents of spl.postinst into zfsutils-linux.postinst may be the right approach.

Other than that, you can probably just drop the zfs-dkms package from the zfs-linux source and then spl-linux should be unnecessary as you note.