Ignorance of a technology is a poor excuse to crap on it. I've used many different technologies over my 15 year career. SQL Server, MySQL, Postgres, MongoDB, Firebase, etc. Each worked well enough, each had it's drawbacks. I'm not here to tell you MongoDB is a silver bullet for every specific use case, but from personal experience I haven't run into an instance where it was a hindrance.
Disclaimer: I currently work for MongoDB.