Why is it problematic if people can’t distinguish between real news and propaganda?

The simple answer is that these people wont know whats real or not. If I was constantly watching a source putting out propaganda that, "People who drive Jeeps will try to hit you on the road," and I belived this, then I would always be paranoid while driving past a Jeep on the road. Even though, in reality, it's not true and they're driving like normal people.

(202 bc - 220 ad) dynasty started by lui bang; a great and long-lasting rule, it discarded the harsh policies of the qin dynasty and adopted confucian principles; han rulers chose officials who passed the civil service exams rather than birth; it was a time of prosperity