Content suitable for graphic expression
Graphics and words are the most primitive of these expressions. Judging from the literary genre, all genres can be presented by pictures and texts.
Such as: novel literature (novels, poems, essays), non-fiction literature (argumentative essays, narratives, reference books).
From the creator's point of view
Creators can keep thinking on paper and computer and revise it back and forth. Only at the moment when the creator finally sends it out can readers see the highest realm that the creator wants to present.
On the one hand, the creator has enough preparation time, on the other hand, he doesn't need to show his face in front of readers (readers often don't even know who the creator is).
We can say that graphics and text are the lowest creative cost among the four.
From the reader's point of view
Humans don't like reading by nature, just like many people say that I have a headache and want to sleep when I see books. Because for readers, pictures and texts need to be seen through eyes and thoughts, which is the highest learning cost.
But because of the high learning cost, in most cases, graphics and words are also the best learning results. Readers themselves need to go through the process of understanding and internalizing knowledge, so they are more impressed.