I'd still argue that this recommendation was aimed at the general populace that is notoriously bad at creating sufficiently secure passwords and passphrases. And I think there's enough evidence for that 
sure, I understand that.but we are abstracting here from the fact that if the "general populace" is bad at creating sufficiently secure passwords, then it is quite likely also bad at securing the copies of their wallet's secret files.
so if they were consistent in heir recommendations, they should basically recommend everyone to stay away form bitcoin. but they don't - they only recommend to not use brain wallets, like it was the very thing that is going to save an idiot from loosing his coins.