That is because by definition and necessity, history only exists after the fact. Add to that the old idiom history is written by the winners, and the waters get muddy fast. Had the Axis won WW2 you can be sure our history books would read very differently today. Academic history is very much a product of the state educational, i.e., indoctrination system. Nothing is more cloistered than a tenured university level history professor. Their slant on history is a brand they have nurtured, and they will protect that version because it is their livelihood and identity. A Marxist and an Objectivist would both have a very different take on history and both be correct in part. Perspective is everything.

Then there is the issue of unintended consequences. That is where history can get real sticky and twisted. In my lifetime I have seen several versions of history completely upended and turned inside out. History gets distorted pretty fast and is prone to succumb to political fad and fashion and is a poor place to be hunting for ultimate truths. History gives us the illusion of importance. We forget we are just bacteria hanging out in the petri dish until the agar dries up.