They need the public at large to be needy, frightened, helpless and dependent. Not expendable, but more like hostages, or livestock, both of which may have value. The armed citizen is neither, and is the autocrat's worst enemy since he doesn't need a douche like Daley to protect him from his neighbor.
I hate to disagree but I will. Stalin and Hitler saw many as exependable. Even those who supported their rotten ideas. As to those who didn't we know what happened to them. As to the unwashed masses many ended up in ovens or died in Gulags.