As an innocuous example of sharing data with pure bash and Arise, these people here have preserved the Trigedasleng dictionary, the fictional language from the science-fiction/young adult show The 100, after another fan site was taken down. They use a github repo as data backend, and Arise as a static-site generator for github pages. All their data are stored in lots of version controlled JSON files instead of a database. According to the authors, this democratizes the process of forking and adding data to the repository.
As for this valid focus on critical mass of users, perhaps a linked tags approach is better than a multiple-communities structure, until specific tags gain enough friction to become communities. Just thinking.