I haven't read all the published adventures, so I don't know this to be true, but assuming you're right, as I suspect you are, I think this rather undercuts @Oofta's claim that it "simply isn't an option" for his Sage character to use their background feature because his group is running through Curse of Strahd, a published adventure which is set in Barovia, that "most background features simply don't apply" in that setting, and that the existence of published adventures set in places like Barovia is evidence that background features are "a bad idea".