Censorship
Censorship is not a top-down reaction chasing down an idea after it has gained popularity. That's Fischer Price's "My First Dictatorship"; some fairy tale plebs tell their children if they do bad things.
Real censorship is a multi-layered process. In order to prevent popularity of an idea, you have to prevent the idea from being spoken.
To get started, you foster an environment where everyone has their own subjective definition of every single word. This can be done by giving everyone nuggets of positive reinforcement (Henceforth referred to as "gold stars") every time they perform behavior that demonstrates their willingness to create their own subjective lexicons. An example of this is to demonstrate clever-sounding hand-waving to describe a situation. The more grandiose the hand-waving, the bigger the gold star.
For instance, if the question is "Why did X happen?" then acceptable ways to get gold stars would be answers likes "God", "racism", "classism", and other shallow attempts to display an understanding of more complex affairs without being held responsible to demonstrate mastery of such complexity. The interface for authority (Parents at first, then community leaders, then mass media) gives the gold star, and the Pavlovian response is established.
This is the first layer of censorship: Rewarding acceptable behavior. The source of these gold stars must be an interface for authority.
This creates the second layer: Associating positivity with interfaces of authority.
This naturally creates an environment where failure to provide gold stars (by failing to accept the hand-waving) is not just a simple misunderstanding of semantics, but is, instead, a direct call for violent, identity-preserving confrontation.
This is the third layer: Punishing those who do not provide gold stars. The interface for authority can never dole out the punishment since the positive Pavlovian reinforcement must never be broken. This means that the offended must be free and even encouraged to punish the offender.
For example, if the question was ("Why does X suffer?") Party A displays standard hand-waving grandiosity ("Because Y oppresses them") and Party B says that's incomplete, ("But Y is a symptom of Z") Party A will fly into a rage and intimidate Party B (By typically shouting, "You're atheist/racist/sexist/terrorist/etc.") until gold stars are procured. Only gold stars can satiate the rage. Once mired in confrontation for even the slightest miscommunication, ideas and words cannot be spread at all.
This is the fourth layer of censorship: Fear of confrontation. As people have ideas in the future, they must filter them against previous examples of communication-inspired conflict. The fear of confrontation will prevent them from sharing the idea. This, unfortunately, does not eliminate the idea, however, and the idea holder may still have their behavior influenced by that idea even subconsciously.
This creates the fifth layer of censorship:** Self-censorship**. Once fear of confrontation has taken hold as the law of the land, people will voluntarily eliminate their own ideas (and anything that is similar) out of fear that simply having them will provoke conflict.