Systemd was a personal project of Lennart, it didn't even originally came from Red Hat. Red Hat certainly hasn't the power to coerce Gnome into anything.

And major distros all had long discussions and debates on public mailing lists where the details of why they adopted it is discussed.

Pretty much. Originally, the Gnome developers told the distros that it wasn't a big deal because logind would run just fine with whatever init system they chose to use. The a few years later once this was deeply embedded in everything Poettering declared that this was never supported, the distros shouldn't have done it, and it would break in the imminent future. The major distros all switched in the next release whether they wanted to or not.

Various people adopted it for various different reasons, and after going through vastly differing decision processes. Consider the contrast between Debian and Arch, for just one example.

* https://news.ycombinator.com/item?id=11834348

openSUSE has a good page explaining why they use it. https://doc.opensuse.org/documentation/leap/reference/html/b...