Not an expert in either so I may be mistaken, but to the best of my knowledge launchd doesn’t have anywhere near the scope of responsibilities or functionality that systemd is capable of/given. It definitely encompasses more than a bare bones init system, but it’s not quite the beast that systemd is.

If by "similar to systemd" you are referencing launchd, not really. The intent of launchd is more along the lines of xinetd[1] than systemd. Here[2] is more info on what launchd is intended to address.

1 - https://en.wikipedia.org/wiki/Xinetd

2 - http://launchd.info/

It's similar in the sense of throwing out the Unix philosophy and replacing it with a different one while keeping 99% of the code. It's not obvious why NeXTBSD would be better than Lennartux though.

(Just to be clear, I never liked the Unix philosophy so I enjoy seeing experiments in postunixism.)

Only part that may be relevant to compare is launchd, and even that stops at systemd-pid1, not the wider systemd project.