Theodore Dalrymple is credited with the quote (I've not read any of his work) that goes something to the effect that the purpose of propaganda is not necessarily to deceive, rather it's to shame or demoralize the populace. That's certainly one possible view, presumably implying that the Inner Party is basically bragging about its power and rubbing the noses of the Proles in their powerlessness.

However, some authors pose another interesting variation. That is that, at least in the case of our present government, the incoherent pronouncements of "narrative" are basically that -- the ever-shifting utterances by a ruling elite that is anything but competent or evil. It's a sign of a failing system, not of a powerful authoritarian one.