This comment helped me to put into words something I've been thinking about recently.

Propaganda that erodes the concept of truth in a society also destroys trust. While a dictator may benefit in the short term from confused opposition, their erosion of truth deeply damages the society on which their power depends.

That being said, I don't know how long a truth-optional trust-destroyed society can last. For instance North Korea, but I know nothing about how much corruption exists there.

(Apologies for being off topic)