Perhaps more than any other form of art, photography is treated as a technical pursuit. That’s not to say that other forms of art can’t be highly technical — they are! — but most people can appreciate a painting without asking about the specific brands of paint used, the wrist action used to apply it, and so on.
The same cannot be said for a photograph. There’s often an expectation that photographers publish their settings with their images. If the f-stops and ISOs don’t fit with the presentation, the expectation is that the photographer will supply them if asked. If the photographer won’t indulge, it’s assumed he or she is hiding something.