Sorry for necro posting on a 4 day old thread, but I wanted to add my 2 cents. The point of lying consistently isn't for anyone to believe what they're saying (as you point out, truth just doesn't matter anymore, see Saddam's WMDs). The point of lying is that hegemonic power is capable of constructing social reality unilaterally and wielding the ability to construct reality to achieve political goals. A huge amount of things that are incredibly relevant to geopolitics, despite being falsifiable and objectively observable, are also possible to simulate through a performance. No bomb has to be planted in a stadium to evacuate the stadium if a bomb threat is called in, and all it takes to make a bomb threat is a phone; imagine what you can do with imperial hegemony!

This phenomenon is seen pervasively in times of crisis: the state will go out and defy reality, which performatively makes reality change in turn (see Biden declaring COVID over, Trump executive order defining trans people out of existence).

So, from a postmodernist perspective, even those who try to reject the reality that is being imposed, must still abide by it. That's what power is: it's not a single, centralized institution; it's actually a strategic situation where some powerful people construct a scenario where the powerless people have to accept their condition, because they understand be worse off if they resisted, at least as individuals.