We don't even have to go back in time far to explain that. In 1969 a nun at a Catholic all girl's high school in Baltimore was murdered for helping the victims of sexual abuse at her school. Turns out multiple priests were sexually abusing the underage students and prostituting them out to others, and the nun was the only one who listened and wanted to help. No one was ever charged with a crime.

Now imagine it's medieval Europe, there's nowhere to run, and Monsieur Pedo has the power to imprison you and have you tortured.