Or rather, why did rms et al dislike UNIX? It seems to come up a lot that they basically settled for a UNIX clone since it was widespread. They certainly didn't care for the philosophy.
Woah Woah Woah, rewind a little. Who built the OS? Linus Torvalds and friends. Who built shitty things into the OS? RMS's Friends/followers. Then you get a bunch college drop outs using these shits at great lengths, ignoring true *nix systems.
So you get a Grad, Linus, that reinvents a *nix system knowing full well it will be more practical than any other OS on the market. GNU only marketed lies, what Merricans only buy, so you get 150+ Linux distros.
IOW, OP, you got sold a lie, and you believed it. RMS is just a prick and delinquent (successful one at too). But again, we can say the same thing about Microsoft, and Apple Inc..