Not only to vision, but themes. Hitchcock was an auteur. Spielberg is an auteur. George Lucas thinks of himself as an auteur as does Bryan Singer. The auteur theory basically assumes that directors are their movies and vice versa (in a very basic sense). Bryan Singer indentifies with being alienated, thus he thrusts that in his films in that many of them deal with this particular theme.
Not every director is an auteur. No, James Cameron probably doesn't consider himself an auteur, but that doesn't mean that other directors don't. But the best directors tend to deal with similar themes throughout a great many of their works. Spielberg speaks a lot about the dangers of knowledge in his work; Lucas thrust his poor relationship with his father into the original Holy Trilogy; Scorsese focuses on the interconnection of people in his work; Hitchcock often spoke on the dark nature of authority and the feeling of being trapped in his work; and Bryan Singer deals with the nature of being alienated and alone in his works.
So, yes, my comment did have a base in the discussion at hand. You claimed that no director should thrust their own lives onto film. But it is the nature of the best directors to have a theme, often personal to them, that runs throughout much of their films.