@colinsmatt11 rms didn't set out to make a Unix clone - he set out to write a free software OS, that happens to be mostly compatible with Unix, but GNU's Not Unix.

The Unix design of having individual programs that do one task made development feasible - they just have to replace the malware piece by piece and eventually a fully free software OS was made.

Unix is a mostly sane OS design and it does work - the main problem is that all Unix implementations were and still are, proprietary malware.