The content of an image should not be confused with the subject.
Content is the result of the approach a photographer takes in resolving the subject into an image. The directness of the approach is what determines whether the content is considered strong or weak.
The fact of the event is paramount, and the manner of its capture is to document this fact as clearly as possible. Image composition is of a practical bent. News photography, or reportage, is the best example.
The treatment of the subject - abstractive, generic and symbolic - is paramount, not the fact of it. A subject is imaged for "what else it is" (Bruce Barnbaum in "The Art of Photography"). Image composition is of an unusual bent. Expressive and abstractive art photography are good examples.
A strong cautionary tale about the seductive tensions between strong and weak content can be in Michael Freeman's "The Photographer's Eye". George Rodger was a photographer who entered Belsen concentration camp alongside Allied troops towards the end of the Second World War. In a later interview, he said:
"When I discovered that I could look at the horror of Belsen - 4,000 dead and starving lying around - and think only of a nice photographic composition, I knew something had happened to me and it had to stop."