The article explains that these items can unexpectedly shed light on historical questions, giving as an example a letter from Marat that seemed to demonstrate h

The article explains that these items can unexpectedly shed light on historical questions, giving as an example a letter from Marat that seemed to demonstrate he was not in an English prison at a time when most historians thought he was. Items in archives are like fossils: remarkably rare, incredibly personal to the entity involved, but potentially of great import to the rest of us because of what we can learn from them. I admit I'm a little tone-deaf and didn't notice any hyperbolic language, but I would encourage you to give the article another chance.