Folks direct a lot of systemd hate at Lennart, but just take a look at the journald header[0]: uint8_t signature[8]; /* "LPKSHHRH" */
== Lennart Poettering, Kay Siver, Harald Hoyer, Red Hat
I don't know the details but I heard at some point Kay and Lennart had a falling out within the project. By the time I got involved in journald development @ CoreOS, neither Kay nor Harald were visibly participating anymore... It was kind of annoying, as it left just Lennart to review any journald PRs, who was obviously busy, but eventually got around to it. I think it's worth noting that despite being the person who receives all the systemd hate, Lennart didn't promptly abandon maintenance of the project after getting installed everywhere.
[0] https://github.com/systemd/systemd/blob/v255/src/libsystemd/...
So for example, Red Hat backing meant that Canonical would have to be pulled in kicking and screaming to use SystemD and Ubuntu is one of, if not the most influential distro in the Linux world.
Ubuntu created and used upstart until it basically lost out to SystemD and had to move over.