[MertsA]

>the best thing they could have done would have been to make it modular.

They did, systemd is very modular in nature. The only things that aren't modular that spring to mind is the journal and systemd the init requires dbus (sort of).

systemd the project has a little bit of everything that you need in an operating system but systemd the init is stripped down to being able to parse unit files, supervise services, and generate and walk the dependency graph from where you currently are to where you're aiming to be.

All of the random features that you always hear about are all individual self contained services. So for example, systemd the init knows nothing about the format of /etc/fstab or SysVInit scripts. It only understands how to work with unit files, the way this works is that there's separate self contained generators that parse /etc/fstab and all of the old init scripts and creates unit files that only exist in a tmpfs directory.

If you don't want something like systemd-networkd then you don't have to have it. You can just compile systemd without it, turn it off at runtime, or just configure systemd to not start said service. You can take systemd and make it suitable for everything from embedded use, to servers, to a multiseat desktop.