Historians don't have a monopoly on truth, nor are they "agenda free", both of which you imply in your many comments. Historians are humans who, try as they might to be "objective", are ultimately still very very subjective. You can read the past spun in entirely different ways depending upon which historian you read.
Historians can write fiction by what truths they cherry pick, or by interpretation that is presented as fact. Fiction writers can write deep truths about the human experience through a made up story. They can transport you out of your shoes into another's.
Upton Sinclair famously said, "It is difficult to get a man to understand something when his salary depends upon his not understanding it.”
It is also difficult to get a person to understand something when their self-image, their identity and the world view they identify with depend on their not understanding it. Is it possible that you are anti-Sinclair, that you feel he is "beat[ing you] over the head with his agenda" because you just don't like it, because it threatens your version of the truth.