Chapter 5 Converting to and from non-tidy formats
Non-tidy data structures, in particular matrcies, is essential in topic modeling where other packages for NLP in R play a major role.
The book has a diagram describing the “glue” part functions in this chapter play:

Figure 5.1: Taken from the book, Chapter 5
As shown in the figure, a tidied DTM is typically equivalent with a one-token-per-row data frame after counting.