What problem is this solving? It seems like boilerplate SQL Alchemy to me. You could probably do away with the schema entirely in a documentdb like mongo and just post your documentation ad-hoc without worrying about schema.
For us the problem we had and attempted to solve was that we wanted automatically generated documentation so that our developers would not need to tediously manage writing API docs for our clients. Our legacy systems already used SQL Alchemy which is the reason we couldn't switch off to a system such a mongo very easily. Overall the goal of our post was just to share how we approached using these tools together. We have internally found the solution pretty elegant and simple for our use cases. Hope you enjoyed!