I don't actually know why this is so hard for people to grasp.
"Hillary Clinton does not eat child brains in the nonexistent basement of a particular pizza place" is not a statement that "Hillary Clinton is a great person and we should do nothing but sing her praises."
But people will climb out of the woodwork to explain how she's "bad" when you make the first point.
As if defending her against a spurious accusation is about her and not about affirming reality.