Its major flaw is it has the ability of choice. Humans can CHOOSE what they believe. Even when confronted with clear and irrefutable evidence, a human can still choose to believe the contrary of the facts.
It is a major problem, because it therefore means that those with the power of persuasion are able to convince others that the facts are not relevant. The only thing that matters is what you CHOOSE to believe.
By this mean, people have been convinced there is an omnipresent, omniscient deity called "God". They have been convinced that tyrants are actually beneficent. They have been convinced that Political Ideology A is far better than Political Ideology B...so much so that the adherents of Political Ideology B are evil. They know something to be true because a journalist has said so.
Do we care who killed JFK. He's dead. Nothing can change that. Do we care if man didn't really go to the moon?
Do we care about anything we choose not to believe? If we don't, then we must make our choices wisely...because a wrong choice can be catastrophic to the individual, or society as a whole.
But worse, when our choice ignores fact, it becomes a very dangerous way for a society to run.
It means we are easily manipulated and controlled.