Toshio Kuratomi (a.badger(a)gmail.com) said:
1) A system admin unfamiliar with systemd installs apache and sees
there's an /etc/init.d/httpd file. He runs /etc/init.d/httpd start to
startup the service unaware that when systemd reboots the service it will be
using the unit file and not the sysvinit script.
/etc/init.d/<foo> start redirects to systemctl; systemd will then start
whichever of the units is 'active' - in this case, it would be the systemd
service both before and after reboot.
2) A system admin unfamiliar with systemd sees that there's an
/etc/init.d/httpd file. He customizes the file for his environment but then
is confused why his customizations aren't being used when the system reboots
(and systemd starts httpd using the unit file).
This is a more likely source of confusion.
Just attempting to clarify current behavior,