History is complicated.
Truth is messy.
Right and wrong are arbitrary creations born of context, like all morality.
People, as a species, are lazy. Right, wrong, truth, facts, and accurate history are difficult and energy consuming to understand. They require thought, and thought is energy.
People don't want to work hard when they can satisfy their desires without it. They don't want truth, right, and reason. They want to fit in the box they are comfortable in, and they want it as easily as they can get it.
People will, to get what they want, warp, twist, contort, and even disregard fact. They will invent their own 'truth' from the vacuum of mindlessness, and demand others honor it. Words, even concepts, have no meaning they will acknowledge for fear of the labor involved in thinking.
In the end, it's all nothing but 'Shut up and give me what I want'.