I remember reading that article. The article spoke like the lessons of an inexperienced developer, and not necessarily the problems of technology they were complaining about. BTW, what do you mean by AQL.

The idea of AQL (ArangoDB Query Language) is to bring an SQL query-like language to a document-store, most notably enabling joins between documents.

Being able to join documents in a query would be very useful in mongo. That is promising to hear that ArangoDB had that feature.