Only with the benefit of hindsight, which isn't helpful to the newcomer.
To someone new who is just trying to work through some web framework tutorial or hack out a half-formed proof of concept, it can be several minutes (or much longer) of trying, failing, copying error messages into Google, and following some guide written for Debian but failing to get it working because you're running Red Hat (or vice versa). When you stack up enough similar problems getting the rest of the stack to work (e.g. configuring Apache or nginx), it stops a lot of new people in their tracks. When they're given something that just works, it's a godsend.
As someone who has worked largely with MySQL until a recent project that is internal to the media enterprise I work for, MongoDB was a godsend in rapidly developing an app that was formerly using MySQL. I faced an extremely tight deadline to rewrite it in order to be ready for a production period for a national publication and it just worked for the purpose of the app.
It otherwise required a lot of state handling of JSON objects on the front end that required a lot of parsing to be compatible with the tables and repairing and rewriting large swaths of that code can still happen, but could not in time for the deadlines.
I was able to pull the whole works together from the ground up (with improved UX) because of the document model. In this case documents are quite the thing being passed around and managed in the application, though.
In the long term, if the app is implemented into larger projects underway, then I would probably set up some sort of persistent store -- but until then it's been eye-openingly great.
For suitable projects, I agree fully. And for smaller applications, or tentative solutions (that are required in some environments) it's a more efficient option.
How is someone like that qualified to work as a software engineer? These were things I did when I was 13 on our old family Pentium, not something I would want a production engineer to do.
That is literally 30 seconds work!