> True, but "nothing but (current) linux, and all linux platforms should use this" is just drawing that line in a circle around yourself.
I don't see a reason to make init portable. sysvinit is portable, but who actually uses it on anything but Linux? Nobody, because pretty much every other Unix out there has its own init, and they're certainly not all portable (cf. SMF on Solaris). And the BSD people won't adopt systemd anyway due to the license.
Also note that while systemd's implementation isn't portable, its interfaces are, so nothing stops a vendor from implementing a systemd clone for their OS.