GNOME and systemd are funded almost completely by Red Hat and their biggest contributors are full-time Red Hat employees.

GNOME does not run at all without systemd.

Even the biggest Linux distros, like Gentoo, struggle to create a patchset to modify GNOME so it does not require systemd; every new version of GNOME takes months to reach Gentoo stable. Most distros have bent the knee and switched to systemd because they had no other option, as GNOME is the most used Linux desktop so they kinda call the shots.