MongoDB is web scale, not universe scale.
Most of the bad things about MongoDB are actually bad things about the NoSQL fad, and that fad was huge around here a few years ago.
It's way easier to understand than relational databases, can be simply browsed and retrieved as json (usefull when your only language is JS) and had good adapters for the cookie cutter frameworks used at the time. And you don't need to bother with a schema or joins.
There are use-cases for NoSQL but it's not a once size fits all solution.