The vision and individual will of Mr Torvalds cannot be discounted as a factor; yes all the communities around Linux did the work but they had not crystallized around a different core.
If M$ hadn't been such pure shits in the late 80s and onward, they could have had a lot of that community themselves. I think, in hindsight, the world may have worked out better for it tho. I can imagine a "source available" xenix based world where M$ plays the role of Apple without the lovingkindness. Imagine a human face being stamped by a "windows update" wait screen... forever.