Upstart existed before systemd. I used to think it was NIH syndrome, but its initial release was in 2006, whereas systemd's was in 2010.
For example, Upstart. RH invents SystemD, Canonical stays with Upstart until, like, 2017 before giving up.
You do want to know the alternative is stable and better for a few years before even thinking to make the change.
It's easy to laugh at the history after it took place.