Why vernacular literature eventually became the preferred way to produce books?

The reason why vernacular literature eventually became the preferred way to produce books is because the "vernacular" was langue that the most people spoke--meaning that far more people were likely to buy books in the vernacular because they could understand them. 

the following best describes postwar era writers in their works:

progressive

many writers,authors,novelists,poets concentrated more on social art and social writing and stayed away from political writings.