I don't understand -- how is this better than a github repo full of json files, with a pre-merge check to enforce the naming format and schema?

The repo will give you integrated authentication, ability to review changes, history, offline capability, ability to test changes locally and many other features for free.

The only downside of github repo is that it is hard to query an object by properties.. but for that you can have an post-merge task that runs after every merge and updates the some sort of database. This will be more complex than a single repo, but still way easier than setting up the whole editing workflow from scratch.