JSON support in PostgrSQL is indeed extremely powerful however it is not as simple.

MongoDB provides "native" document persistence for programming languages, where with PostgreSQL JSON you have to live in relational database SQL land

1. Postgres's json is limited to standard json. MongoDB supports additional scalar types, like blobs and dates.

2. MongoDB's drivers are designed to handle documents. If you use postgres directly, you have to build that part yourself (effectively a kind of ORM, including a query builder)