The thing is, Postgres has grown to where it is without being commercially maintained. So the open-source ecosystem is proven for Postgres. Whereas RethinkDB

The thing is, Postgres has grown to where it is without being commercially maintained. So the open-source ecosystem is proven for Postgres. Whereas RethinkDB was primarily developed by one company, then open-sourced. I hope that the RethinkDB project is successful, but it's reasonable to suggest that the future of Postgres is 'safer' at the current time.