Originally systemd was positioned by Lennart Poettering as a drop-in replacement for the System V init subsystem with the goal of speeding up system startup by parallelizing service startup where possible. An admirable objective!
However, the scope of systemd has slowly increased to encompass the Linux kernel, system logging and lots more. This is craziness. It is now serious blotware with numerous binaries. Like a cancer, systemd is now spreading to more and more Linux subsystems. Worse, we now have apologists for systemd claiming that the old SysV init shell scripts were too complex to understand (actually they were easy to understand) and that if you are opposed to systemd you obviously do not know what you are talking about.