Seemingly 2 other people worked on it as well, one from Red Hat and one from Intel.

Also bear this in mind:

All the user-space utilities hard-depend on systemd. Without systemd, you’d need to write your own utilities that make use of my kernel patches. Something needs to manage cgroups in your system, and that something needs to enable the right cgroup controllers and set the right limits (see also the long-winded explanation about how this works).