Missed some rows

Dude, neither the sysvinit init binary is portable, nor the init scripts. In fact the init scripts are the best example for non-portability: you can't even really write them in away to be portable between distros -- let alone kernels/OSes.

In fact you can turn this all around and claim that systemd improves portability here -- the portability between various Linux distributions for upstream packages: because they can just hook themselves into the boot in a single unified way, that is the same on all distros (which have adopted systemd).

So if you say that systemd was worse with portability I say it actually drastically improves it.