[ValdikSS]

Linux (the kernel) has LOTS of functionality anyone barely use or even know. Without that, there's no tooling around this functionality, no adoption. Not even all TCP socket options (setsockopt) are documented!

Systemd pushed forward proper usage of capabilities, better watchdogs (in a broader sense, as systemd supports all kinds of them), isolation, policies, and so on and so forth. You need it all to efficiently control the daemons, and it's great when it's all available in a single suite.

[direwolf20]

Because of SystemD, you can't use Linux control groups. On systemd systems, only systemd is allowed to touch control groups. I think they even tried to make the kernel enforce this but they failed, so now it just breaks systemd if you do.