UNIX never meant anything. z/OS is UNIX. Even the Single UNIX Spec never clarified anything other than "UNIX includes these things". People who rail about how systemd "isn't UNIX" never had to maintain a heterogenous environment of IRIX, Tru64, HP-UX, AIX, and Solaris. They're all UNIX. OSX is also UNIX. Guess how similar they are and how many design philosophies they share.

Coreutils has a lot of binaries that do different things. Is is monolithic? The GNU ecosystem and autotools barely function without other GNU tools which aren't part of the same project. Are those monolithic? Monolithic is a canard.