And they don't have this why?

[Abacus]

No, I said that the territory conquered encompassed millions of worlds. In that, there are likely lots of worlds there that had defenses (i.e. a shield) that makes quick conquest problematic if they wanted to hold out. Even (relatively) tiny Naboo got a planetary shield before the Clone Wars (AOTC ICS). And after the Clone Wars, the number of defended planets probably went up a good deal. Psychological warfare alone cannot possibly be all it takes to cow, conqueror, or hold all of these worlds.

On that note:

I'd say that it is quite possible. If there are enough examples for your "overlord" to utterly destroy any resistance you are likely to offer, previous examples having been made, then that makes it much more likely I will rather be complacent and wait until my ruler's power is shown to be fallible.

Such as when the 1st DS was blown up, a lot of worlds rebelled. Then the Emperor had them all savagely put down. The Rebellion was actually at its weakest after the destruction of the 1st DS and was not fully back on track until a few years after the Hoth Campaign, which weakened them again. It wasn't until you had the verifiable evidence for the death of Palpatine, all central control, that you had worlds rebelling en masse and a significant number of Imperial officers and moffs going rogue.

So I think that the psychological aspects of Thrawn's campaign were both accurate and impressive at the same time. However such an action requires you to be continually successful. Any slacking off of your inertia and your illusion of infallibility is over. It's a very thin line to walk, but not impossible. Various real life armies and nations have used this technique: Macedonians, Romans, Swedes, Spanish (armada), German Wehrmacht, Soviet Empire, etc.

[Illuminatus Primus]

Its not that simple, all those listed powers had the actual forces in the field to dominate the enemy, not just the illusion of it.

[Abacus]

Its not that simple, all those listed powers had the actual forces in the field to dominate the enemy, not just the illusion of it.

The Empire most certainly had the forces to dominate the enemy, which was exemplified by the entire campaign, which only reversed when Thrawn himself died. It's fairly similar to ancient Roman emperors being the driving force behind a campaign, and after their deaths those campaigns slack off and come to a halt.