A perhaps important clarification:
Many of those, including Linux as far as I know, simply started as projects that were driven by single authors with a strong vision and remarkable diligence.
Then people flocked to those projects, but with the understanding and appreciation of that vision.
I don’t think any of them wanted to be BDFLs for the sake of power. They were the original authors and _made_ something useful. I don’t think any of them took over an existing project and declared themselves dictators. Ironically they all would be way too opinionated to do so.