In the context of UNIX development, portability actually means the system can
operate different computer architectures (in the 70s, every computer
architecture had its own operating system).
Anyway, who can list programs that do not run on a system with systemd? Or
even programs that required significant alterations so that they could run on
a system with systemd? I am not talking about taking advantages of systemd's
new features. Just compatibility.
Second question: should GNU/Linux never take advantage of the most advanced
features in Linux (such as the cgroups) because the less popular kernels
(BSD, Hurd) do not have them? A yes answers means our operating system cannot
evolve faster than the least active kernel projects.
