Eco was right about that, but he failed to note that this phenomenon is not unique to "fascists" (right-wing authoritarians), but is also found amongst the left-wing ones as well. In fact, I would argue that it is even more pronounced on the Left.
it's a universal propaganda tactic, you see it everywhere
venezuela:
>americans are weak decadent capitalists who can't touch our glorious bolivarian revolution
>americans are also an overwhelmingly powerful evil empire that is at fault for ruining our economy with blockades and sanctions
islam:
>infidels are pathetic dogs who fear the might of allah, victory for the glorious mujahideen is assured
>infidel colonialists and their jewish machinations are at fault for all our states failing and collapsing
russia:
>america is a failing dying empire desperately trying to cling to what little relevance it has left!
>american imperialism is a grave danger and existential threat to poor innocent russias national security!
nazis:
>jews are pathetic subhuman parasites who are good for nothing and do nothing but ruin everything they touch!
>jews secretly control the whole world through secret conspiracies and financial networks that go back hundreds of years!
USSR:
>capitalism is slowly dying, the rise and triumph of world socialism is inevitable, we will bury you!
>capitalist pigdogs are ruining everything with their economic and financial systems and made our glorious socialist state collapse while america prospers!