I sometimes visit such wikis, and my feeling is they often wouldn't fit in Wikipedia. It's mainly an issue of perspective. Take, for example, these two entries

I sometimes visit such wikis, and my feeling is they often wouldn't fit in Wikipedia. It's mainly an issue of perspective. Take, for example, these two entries on the same fictional character: http://finalfantasy.wikia.com/wiki/Aerith_Gainsborough http://finalfantasy.wikia.com/wiki/Aerith_Gainsborough, https://en.wikipedia.org/wiki/Aerith_Gainsborough https://en.wikipedia.org/wiki/Aerith_Gainsborough The one from the Final Fantasy Wiki is from the perspective of a Final Fantasy fan, and is generally for a Final Fantasy fan. That is, it's explaining how Aerith relates to the rest of Final Fantasy. Some of it flirts with being in-fiction. The Wikipedia article is more about how Aerith the fictional character relates to the real world. My point is that the people who want to maintain the versions that are more in-fiction may not also want to maintain versions that are more focused to how this fictional thing relates to the real world.