What's really relevant is market share. Guess what? Systemd is winning because it massively sucks less than what existed before it.
It's Embrace Extend Extinguish in action, except by using the force of running two biggest distributions in addition to GNOME project. (And a bunch of others depending directly on them.) Even Debian was unable to weather all the dependencies using the new interfaces. Gentoo tries still with OpenRC, more or less successfully.
Then there's Fedora, which is upstream of Red Hat, who has many of it's contributors as Red Hat employees, so I don't see how it's odd that they would adopt software that Red Hat are invested in.