I got some feedback in person from a MongoDB user at one of our recent conferences:

The user had a typo in the collection name they targeted when using mongoexport and as a result they exported an empty result. However since they did not get feedback from mongoexport that the collection did not exist, they didn't realize until later that they'd made the mistake and were frustrated.

Ideally we would provide some kind of feedback to the user when targeting a non-existent collection rather than making it feel like the operation was successful (even if we have indeed successfully dumped an empty file).

They found out how to use mongoexport from the Atlas in-UI Command Line tools helper page.

This may apply to mongodump as well (I'm not sure).