Yes, photos of naked people are used to extort them (usually into just paying the holder to delete them).

https://news.ycombinator.com/item?id=42261730

This raises a different but related question. In what world should a victim of a crime be extorted for doing innocent things in their home. If a peeping tom took a photo though a window, could that be used to extort someone?

When people are extorted for these kinds of things it's usually catfishing that leads to sexual acts being recorded. That's not related to cybersecurity.