Further down in the comments you'll find a research paper [1] that analyzed why Wikipedia succeeded where others failed. I am not sure I bought into the conclus

Further down in the comments you'll find a research paper [1] that analyzed why Wikipedia succeeded where others failed. I am not sure I bought into the conclusion (which prompted my initial comment), but at least it has a comprehensive listing of all the main players at the time: Interpedia, TDEP, Everything2, h2g2, TheInfo, Nupedia, GNE [1] https://mako.cc/academic/hill-almost_wikipedia-DRAFT.pdf https://mako.cc/academic/hill-almost_wikipedia-DRAFT.pdf