Orwell's 1984 government?
Because it's an efficient way to deal with dissent. If they allowed rebellious notions, the ideals would leak to the Proles and the government employees, eventually leading to a outbreak of violent uprising which would cripple their empire. Eurasia and Eastasia would then be able to invade Oceanic strongholds and for incorporate it into their respective nations. Unless ther civilian population was then violently supressed, rebellions would likely begin to occur in the two other superpowers, and then bye-bye totalitarian empires.