I believe that one of the big things that diagrams help with is maintaining state while having a conversation. You don't have to keep track of so many things in your head and it works in a similar way to the "tell ’em what you’re gonna tell ’em, tell ’em, and then tell ’em what you’ve told ’em" style of presenting--your audience gets to see up front what journey you are taking them on.

There's a great book by Abby Covert about diagrams in general: "Stuck? Diagrams help."[1]

From a learning perspective, having multimodal[2] options, such as a mix of visual (diagrams), reading, and videos/audio can really help with onboarding. Different people learn better with different methods, and different methods work better in different contexts, for example I personally hate sitting at my desk watching a video, but enjoy doing so on my phone while commuting.

[1] https://abbycovert.com/stuck/ [2] https://www.learnupon.com/blog/multimodal-learning/