Realized it might be worth providing a concrete example. So here that is -- The GNU Manifesto has a whole section, "Why GNU will be compatible with Unix", that

Realized it might be worth providing a concrete example. So here that is -- The GNU Manifesto has a whole section, "Why GNU will be compatible with Unix", that briefly explains why RMS chose Unix. In it, he fairly explicitly states that Unix is not his ideal software system, but it's a good choice for advancing GNU's political goals. In other words, the politics are considered at least as important as, and perhaps more important than, developing quality software.