Because I know people who have been harassed and raped and whose harassers and rapists weren't punished.

I know literally dozens of stories like that, and maybe a handful where the harasser or rapist was punished at all. Of those, even fewer where they were convicted of a crime.

The majority of these cases the victim isn't public in their accusation, there's no argument that they're trying to gain something or hurt someone else. So by comparing the data that is presumably more honest, that people make in private, to that in public, we can assume that most instances of harassment go unpunished.