It depends on your use case, and RDBMS isn't the best option for all needs. Mongo's approach is pretty useable. That said, there are alternatives, you can get

It depends on your use case, and RDBMS isn't the best option for all needs. Mongo's approach is pretty useable. That said, there are alternatives, you can get very similar characteristics, though a more painful devex out of say CockroachDB with (key:string, value: JSONB) tables. The only thing I really don't care for is managing Mongo... as a developer, using it is pretty joyous assuming you can get into the query mindset of how to use it. Also, if you're considering Mongo, you might also want to consider looking at Cassandra/ScyllaDB or CockroachDB as alternatives that might be a better fit for your needs that are IMO, easier to administer.