I'd just like to interject for a moment. What you're refering to as GNU/Linux, is in fact, systemd/GNU/Linux, or as I've recently taken to calling it, systemd plus GNU plus Linux. GNU/Linux is not an operating system unto itself, but rather another free component of a fully functioning systemd init system made useful by the systemd daemons, shell utilities and redundant system components comprising a full init system as defined by systemd itself.

Many computer users run a modified version of the systemd init system every day, without realizing it. Through a peculiar turn of events, the version of systemd which is widely used today is often called GNU/Linux, and many of its users are not aware that it is basically the systemd init system, developed by the Red Hat.

There really is a GNU/Linux, and these people are using it, but it is just a part of the init system they use. GNU/Linux is the os: a collection of programs that can be run by the init system. The operating system is an essential part of an init system, but useless by itself; it can only function in the context of a complete init system. GNU/Linux is normally used in combination with the systemd init system: the whole system is basically systwmd with GNU/Linux added, or systemd/GNU/Linux. All the so-called GNU/Linux distributions are really distributions of systemd/GNU/Linux!