According to the preface, who benefits when a detailed Guru biography is written and studied?

Chapter 0 explains that multiple individuals and even divine principles benefit from the creation and study of a detailed poetic Guru biography. The writer performs Guru service through the act of composition. Simultaneously, when other devotees study and perform Parayans of the book, the writer gains the merit of serving God in humanity (Jan-Janardan). The devotees who study the work also achieve the purpose of their lives, and ultimately, the Sadguru accepts this service from both the writer and the congregation of devotees.