If some foreground elements are put in front of the viewer, partially obscuring the subject, the viewer would take the position of an unseen observer. Especially if the artist chooses to hint malicious intent, a member of the audience might feel uncomfortable looking through the eyes of a stalker.
When foreground elements obscure the subject from view, viewers are placed in the position of an unseen observer. If the artist intentionally suggests malice, it can make the viewer uncomfortable viewing the scene as if they were being watched by a stalker.