[kazinator]

This is not the complete picture. Stallman decided to reimplement Unix because it had a combination of popularity and technical merit.

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.