This is the most dangerous form of censorship: when people are led to believe (or told) that they are getting an unbiased set of ideas and information while it'

This is the most dangerous form of censorship: when people are led to believe (or told) that they are getting an unbiased set of ideas and information while it's not unbiased. Under dictatorships it's common to claim that all conversations are allowed except fear mongering, spreading enemy propaganda and outlandish claims. Over time the "Overton window" of what is considered not outlandish in public debate grows smaller. For example, during WW2 there were rumors in Germany about extermination camps that were dismissed as "crazy conspiracy theories". Covertly manipulating the public opinion by suggesting some content instead of something else is easy to implement, effective and difficult to detect.