To flesh this out, let me see the volume of calls and data from one place to another. Help diagnose back-pressure, drops, rejections, and any other irregularities.

Think of an on-caller who wants to quickly pinpoint a problem. Visualization could help one understand the nature of the problem before reading the code. Then you could select a part of the visualization and ask the computer to tell you what that part does, if there are any recent changes to it, etc.