I never knew that fanlore existed! I think it would be a good platform. The journal system allows for a pretty easy organization and would easily be accessible to reference.

It looks like the issue is that many fanwriters/artists in smaller fandoms feel like they don't have a place in AO3 due to lack of ways to tag their work and lack of works that are in their fandoms. A lack of representation means that they aren't inclined to post.

I don't think this was intended. I tend to assume that most people don't know a lot of fandoms and that includes the folks at AO3. If they were directed to the proper place, then they could find all the relevant character tags that were needed, outreach to the fandoms and hope that it takes.