You've got cause and effect backwards. Societies have to overreact to pandemics, because those that didn't got wiped out - eventually. Enforcement of quarantine and similar measures through extreme social norms is a necessary adaptation to the threat of plague; civilization wouldn't be able to exist without it.
You think that the authorities are creating an internal enemy to sow division. I am saying that the visceral reaction to plague is an instinctive human universal, not something that has to be cultivated.
