Hi genec
Those files actually do something very useful. By providing an access point to the boot up and
shutdown process they greatly reduce the temptation to modify the system boot and shutdown
scripts.
always remain for the user (as opposed to distro/extension authors; end user or remastering user)
They are there to modify the behavior from the base system. Extension authors sometimes include
instructions to modify those files. You as an end user or in re-mastering are free to change them too.
I'm not sure what you mean by "user as opposed to end user".