Not having to go on an hour-long googling adventure to figure out how to write a simple init script. If you know bash, that's all you need if you're running (for instance) OpenRC. Systemd services are a mishmash of obscure setting names.
It's easier to manage/secure since it's essentially just shell scripts. Systemd touches a lot of things and makes the initialization process more complex, which introduces more security vectors.
Because I left Windows precisely to avoid the kind of shittery that systemd is doing.
It's absolutely no coincidence that the people who have developed the stuff that's brought the most degradation to Linux - systemd, PulseAudio, Gnome's "user has no right to themes" attitude - all come from a Microsoft background or explicitly work for Microsoft.
I'd have far less of a problem if systemd was split into more practical, actually independent things that actually worked and distros didn't buy their snake oil so easily. But for the time being, to me, the systemd experience is pretty much like the PulseAudio experience, what with the whole "waiting 120 seconds for a network interface to activate that it's not going to because it's the damn ethernet port and I'm on the road so the cable is not connected, stupid letter-potter dipshit".
Systemd is an init system (the first process that manages/runs everything else). However it does far more than a traditional init system; arguably it's tendrils are all over mainstream Linux now.
GLIBC is the GNU Project's implementation of the C standard library. It is a wrapper around system calls of the kernel for application use.
To be fair, I don't think systemd is classified as just an init system anymore. It's a software suite that just "conveniently" happened to have an init system included.
I agree, some of us just want a simple init system that isn't millions of lines of code and to be able to pick our own parts to use in a UNIXY fashion - If it ain't broke why fix it...
For example on my alpine system I have acpid, crond, dhcpcd, openntpd, seatd, udev, wpa_supplicant as services that systemd would replace.
