1107. What’s the harm in the photographer putting words or graphics onto the image area?

It's a matter of principle: the public is told that no photograph can meet the  Trust Test (see P1) if it depicts anything that was not “recorded during the relevant exposure(s) using the portion of the light spectrum that is visible to humans.”

Viewers are told to disregard the TTG label (see #4) if they believe that any words, logos, or graphics on the image area were applied by anyone other than the {third party} entity publishing the photo.

On a practical level, if the policy were otherwise a photographer could overlay something onto the image area to obscure a deceptive or important aspect of the photo.

1108: Who is allowed to overlay anything onto the image area of a TTG-labeled photo?