It’s fundamental that some members of the public are problems. By prohibiting the content but keeping the people around, they are curating a culture where predators are allowed to roam on the platform as long as they don’t cross a specific line.
They do this because acknowledging and dealing with bad users would also mean impacting fake users that make them money with ad fraud, growth metrics and ginning up engagement.
End of the day, if you operate a social platform, and you have people uploading child pornography and animal torture video, you should do everything in your power to make the user go away, for good.