How does McCloud view comics as visually rhetorical?

I think McCloud views comics as visually rhetorical because there was a section where he discusses how art and pictures are judged using completely separate standards.  In a given comic, the visuals can be more important, less important or equally important to the words.  I was also given the impression during the reading that most people writing a comic would try to make both the words and pictures necessary so the reader pays attention to both parts.  This section was effective, but I felt like in the rest of the reading I hardly looked at the pictures at all except for where pictures were being used as an example, making the pictures unnecessary for much of what he was trying to say.  I also thought it was interesting that he said both "a huge range of human experiences can be portrayed in comics through either words or pictures" as well as "comics have become firmly identified with the art of storytelling."  Both these points made me think more about comics and their effectiveness.  I think that (sometimes) for someone to fully understand a concept, you need words and pictures for them to fully understand what you're trying to tell them.  Assuming people think that visuals are rhetorical in many cases, then it also seems to me that by containing pictures alone comics would be considered visually rhetorical.  All in all, I feel like McCloud's overall point was that comics can be very effective because they contain both words and pictures and that both of them combine to make a stronger rhetorical statement than many other forms of multimedia.