With a feature like this is there still a good reason to use MongoDB?
Honest question, I know Oracle and Postges well, but not their JSON features. I'm just starting to learn MongoDB seriously because of a current project.
Not really, imo. The biggest advantage of Mongo was being able to store a single hierarchical document and search it. Now that you can do that in the RDBMS there's no advantage at all. You also throw away all capability of doing relations in the database with Mongo which is optional in an RDBMS and sometimes very beneficial.
Mongo could win if it were more performant or had a better query syntax... but it isn't and it doesn't. It might have some slight advantage in the speed you can set up a replicated cluster but you'll pay long-term in overall performance from my experience. If all you are doing is storing documents, just use an S3 bucket, etc...
To me the only really good reason to use MongoDB those days is very high data ingestion rate. It was the main reason why CERN used it in the LHC, but I don't know if that solution is still in place.
Honest question, I know Oracle and Postges well, but not their JSON features. I'm just starting to learn MongoDB seriously because of a current project.