That is true. There are linux distros around with musl/busybox (alpine) and some distros without systemd. But i would really appreciate a fsf-conform distro with a fsf-conform BSD-kernel and the bsd userland - it's just a nice addition to the existing oss-os world. It is not about "this OR that" - why not have both?

p.s. both runit and openrc are close enough to the unix philosophy

p.s.s. yes, macos derived from openBSD and is using a sytemd-like init, but - as said - macos mainly targets end-user system... it's o'right for that - i think power users prefer os-designs closer to the unix philosophy.