"You need a database not a message broker" is bad advice, because a message broker is a database, albeit a fairly specialised one. Whether you want a message broker or a more traditional database really depends on which side of the CAP theorem you want to fail on. If you can tolerate consistency failures, you want a message broker. If you can tolerate availability failures, you want a database. (And of course if you can't tolerate either then you're out of luck, because you are going to have network partitions.)