To critique diagrams, consider that they're *for* different things to three different audiences: *creator*, *absorbers*, *users*.
If you're the **creator**, they can be a Sense-Making tool. They can help crystallize your thoughts as you think them or write them down. That is a benefit to *you*. Do not – *not* – think the reader will necessarily get the same benefit.
If you're an **absorber**, you're coming to the diagram under the presumption that it summarizes what the author intends for you to learn. When it is used to illustrate the more detailed text, I think that’s fine. You read some text and then, when it suits you, you glance over to the diagram to see if the picture matches what you think the text said. It’s a cross-check.
But an absorber will have a considerably lower tolerance for detail and complexity than the creator. Creators need to take that into account. Frequently, it's good to eschew the grand diagram that shows *everything*, but rather split into focused diagrams that can be absorbed independently.
An aborber who leans more heavily on the diagram than on the text is likely to have a hard time. Don't tempt them.
I generally prefer to treat the reader as a **user** rather than an absorber. You want them to read the diagram with a goal other than to absorb it as a network of connected facts. Instead, the diagram should be tailored to some task other than general "grokking" of the whole of the solution.