I don't think it breaks down (as long as most of the data comes form the database). For example i know exactly how paymoapp.com (similar to basecamp) is structu

I don't think it breaks down (as long as most of the data comes form the database). For example i know exactly how paymoapp.com (similar to basecamp) is structured , i consider it to be a fairly large system and i know for a fact that PostgREST can support that. As for the "very similar be done for GraphQL", there is https://github.com/postgraphql/postgraphql https://github.com/postgraphql/postgraphql which was based on postgrest ideas. Another approach would be to build graphql on top of postgrest (my comment below)