very tricky and very difficult
A few people find diagrams unhelpful; but many people who regularly use words find the discipline of conveying ideas in diagrammatic form both sharpens their understanding of the ideas and opens their eyes to alternative views.
Diagrams are, like words, intensely personal ways of sharing information and seeing someone else's ideas in diagrammatic form can give a new view of what they are trying to communicate. Diagrams can also suggest new and unexpected relationships between ideas about a situation and new and unexpected ways of moving forward in a situation.
A major point about diagrams is that some people naturally relate well to them and use them frequently, while others tend to prefer textual material. The former are sometimes referred to as visualisers and the latter as verbalisers.
There is nothing wrong with either of these tendencies, but in subjects like systems thinking, social science or technology, where text and diagrams support each other, it is important to be comfortable with both.
In addition, it is helpful to remember that one's own preference is unlikely to suit everyone.
So when verbalisers communicate they need to make an effort to use diagrams to supplement, or even replace words, while visualisers need to remember that for some people diagrams need more textual support than they might expect.
Cognitive style plays a large part in the way we use and see diagrams. As a generalization, men tend to prefer linear processes with clear cause and effect while women tend to prefer associative logic and situations where cause and effect are less clear.
Similarly, men tend to use exclusive, either/or thinking which can be developed into matrices or algorithms while women are more likely to use inclusive modes of thought, disliking either/or scenarios and are more comfortable than men with parallel or multiple processes.
Both the clarity and linearity sought by many men and the interrelationships considered important by many women are relevant to the use and usefulness of diagrams and need to be considered in each instance where a diagram is being chosen to represent a situation.
Diagrams are used extensively in most types of texts, but why do authors use them?
There are two main reasons:
to illustrate what something looks like;
to demonstrate how objects or ideas or quantities are organized or related.
But there is also a subsidiary reason I hinted at.
Authors also use diagrams:
to decorate and enhance the text to make it more pleasing to read.
However this is only one side of the situation, as such diagrams are usually intended to passively communicate models from one person to many (authors to readers). The main power in diagrams comes from an individual or group using them to actively further their own thinking.
Although you need to do a lot of the former activity as a student or an employee, it is the latter activity that is central to much systems work.