I think if Richard Stallman had no qualms about proprietary software, he would have remained in the Lisp machine world, either working for Symbolics or Lisp Mac

I think if Richard Stallman had no qualms about proprietary software, he would have remained in the Lisp machine world, either working for Symbolics or Lisp Machines, Inc., or perhaps starting his own thing. Stallman was a Lisp hacker before starting GNU, and even when deciding on cloning Unix instead of creating a free Lisp-based OS, one of his first projects was GNU Emacs. An interesting thought experiment is what Stallman would’ve done in that alternate timeline in the late 1980s and early 1990s when Lisp machines were killed off by advances in commodity hardware and compiler technology, the end of the Cold War (the US military was a large customer of Lisp machines), and the AI winter (Lisp used to be synonymous with AI).