There are visualizations in your head, and visualizations that you can look at and read and write. Unless you have a photographic memory, IME they're not used the same way.
For example, take their database schema diagram. The graph layout doesn't even make a lot of visual sense, and the visual language doesn't show the connections between columns and relations. But you can "read" through the column names (including the keys they put at top), and trace through the arrows, to see how to navigate to the information you need. And it summarizes important information in a small amount of space. All useful. But that's probably not how you see it in your head, and that's good.