Back in the day, when I was writing novels, someone explained to me that half of the reason for showing things was so the reader could visualize what was going on. The other half is characterization of the viewpoint character, by what and how they notice things.
That still holds true for nonfiction, except WE are the viewpoint characters. And by means of what we choose to focus on, and how we focus, readers are coming to know and understand us.