I briefly read their doc, I think being able to migrate my data from one host to another is really great, but I'm unclear about the concept of repository. acco

I briefly read their doc, I think being able to migrate my data from one host to another is really great, but I'm unclear about the concept of repository. according to the doc, it seems that data stays in repositories. A repository is a user-signed storage, representing all data created by a user. does that mean, this protocol is only suitable for twitter/blog type of applications? I'm thinking about forums/BBS/Reddit, on which data (a thread) is not owned by a specific user, but by a forum board?