because there was no easy/centralized way to spread propaganda. One had to use terror/fear to stay in power. The truth was obvious, so somebody had to keep population scared, so they don't revolt. Nowadays, subtle propaganda works. You air day and night stuff explaining people that white is black and black is white and this works. People see the truth, want to revolt, but then "the experts" from the silver box explain that the opposite is actually true. Everybody happy thinking they are free while they are slaves to the banks and constantly monitored by the Government.