[minimaxir]

Ideally you should be using Postgres or any other relational database instead of MongoDB for technical reasons other than document storage. (e.g. ACID)

Document storage in Postgres is a best-of-both-worlds approach (can store documents w/ ACID), with advantages of MongoDB and fewer downsides. But it's still relatively new functionality. (I've seen use cases of document storage for logging in-database and other quick-write/read-rarely data that would be a pain to normalize with consistent schema, which seems compelling)