Every DBMS comes with its own set of special problems. Most people only find out about the truly tricky ones once they have deployed a database in production (i.e. when it is too late to decide your needs are actually not served all that well by what you chose).
Once a DBMS like MongoDB gets popular, then people uncover some of its failings and write about them...which is great because it means you don't have to discover the same things the hard way. But it's a drag too because there's no database system that everyone agrees is adequate (much less ideal) for every application.
Once a DBMS like MongoDB gets popular, then people uncover some of its failings and write about them...which is great because it means you don't have to discover the same things the hard way. But it's a drag too because there's no database system that everyone agrees is adequate (much less ideal) for every application.