Plenty embedded projects developed today don't use them (and functional desktop and server distros without them are around), "nearly as essential as the kernel" is really overstating it.
It is miles better than SysV or monit. I haven't needed to try the 'suggested' replacements like runit or openrc.
Not every nail needs to be hut by the systemd hammer. We've had really fantastic and light weight init systems for decades without all the bloat and creep of systemd.