You bring up a really good point - that is the UNIX philosophy, but UNIX didn't win the datacenter wars: Linux did. And Linux doesn't entirely share that philosophy; depending on the Linux release it can be the polar opposite; piling on feature after feature into a monolithic block like systemd.
That's not an indictment of systemd... it's just an example of how I'm not sure everyone has glommed on to the fact that just a GNU isn't UNIX neither is Linux.
systemd is a really recent development. Linux won the datacenter wars well before any of the recent desktop stuff started encroaching, and it did it on the back of being a free Unix clone.
It is, but even the raft of features found in some GNU command line utilities are probably beyond the classic UNIX philosophy of small and simple tools.
That's not an indictment of systemd... it's just an example of how I'm not sure everyone has glommed on to the fact that just a GNU isn't UNIX neither is Linux.