The problem with banning things is actually a bit more subtle than just that. Propaganda in isolation isn't necessarily a good or a bad thing. If Big Vegetable embarks on a multi-billion dollar campaign to push pro-vegetable propaganda, that is probably a win for the rest of us. But if Big Tobacco does something similar it is more of a loss.
So we need a mechanism to decide if a specific type of propaganda is acceptable or not. And, if governments get involved, typically they will start restricting propaganda that is truthful but threatening to their chances of holding power (ie, people pointing out the flawed nature of the powers that be). It is better force people to fight propaganda with counter-propaganda and let individuals make their own mistakes.
> It is better force people to fight propaganda with counter-propaganda and let individuals make their own mistakes
The problem is information flow. Propaganda vs propaganda, nowadays, is in-group information and desires fighting against other in-group information and desires.
The lack and importance of truth, facts, the bread and butter of journalists, investigators and scientist, gets out of focus because of governments and other actors blocking access to data, events, locations, partially because often enough, people asking for access tamper with the evidence or start to run all kinds of narratives that would impede an investigation and results that could be 'useful'. There is, of course, much more to all that.
So we need a mechanism to decide if a specific type of propaganda is acceptable or not. And, if governments get involved, typically they will start restricting propaganda that is truthful but threatening to their chances of holding power (ie, people pointing out the flawed nature of the powers that be). It is better force people to fight propaganda with counter-propaganda and let individuals make their own mistakes.