Earlier quoted context omitted.
Unix wasn't given away for free; it was strapped by AT&T licensing and you needed hardware that certainly wasn't free, and not still not affordable to individual consumers. But Unix was a resource-efficient system that scaled down to cheaper hardware with less RAM. Even the dyed-in-the-wool Lisp enthusiasts headed by Richard Stallman were compelled to reproduce Unix, even though their stated goal was to have a system…
Stallman decided to reimplement Unix because it was popular , not because it was somehow better suited to the hardware. One of the first GNU programs he released was indeed his "system running Lisp"; it was called Emacs.
For instance, MS-DOS had a larger installed base than Unix at the time, but ... enough said about that, right?
Imitation is the sincerest form of flattery, as the saying goes.
A hacker like RMS isn't going to pour years of coding into making a C compiler, and Unix utilities, in his spare time, if he thinks those technologies do not have merit.