I tend to have a reputation for being anti-graphics in technical communication. I’m not. I think graphics can be very powerful, if used appropriately. But I also think that graphics are very often used badly, and that a bad graphic is even worse than bad text.
The problem, it seems to me, is that graphics have no inherent grammar. Unless a paragraph is truly butchered, you can usually puzzle out its meaning, because a language has only one grammar, one way of putting words together to make meaning. But what is the consistent and agreed meaning of a thick arrow versus a thin, a circle next to a triangle, or a broken line versus a solid one? When a graphic fails, therefore, it fails utterly.