RMS created the foundations for the existence of a fully-free OS, both technically and socially. He created the concept of copyleft and the GNU GPL, a fundament

RMS created the foundations for the existence of a fully-free OS, both technically and socially. He created the concept of copyleft and the GNU GPL, a fundamental feature of the free software movement. He founded GNU and FSF which remain important enough to be notable. Even the Linux kernel started off with a weird non-free license until Torvalds decided the GPL was a good fit, changing his views on commercial-restrictions after hearing RMS talk. RMS is a philosopher of sorts and is already seen historically as a fundamentally important figure in the philosophy and ethics of technology. Sure, the ideas would be out there some way even if RMS wasn't around. Similarly, biological evolution was inherently an idea that was even being thought about by others at the time of Darwin, but we still acknowledge Darwin's major contributions even though we'd almost certainly at some point know everything we know now even if Darwin had never published anything.