the propagation of misinformation is asymmetrical. a single person or group of people will not have the resources to counterbalance misinfo when its bankrolled by state actors or malicious groups who use it as a weapon. additionally, it's a lot harder to deconstruct a heavily-propagated lie and to educate people than it is to manufacture outrage (eg https://cognitiveresearchjournal.springeropen.com/articles/1...).

what you're describing is an ideal world where everyone thinks and acts rationally and is willing to change their views when new information is presented. that is far from reality. in short, propaganda works for a reason.