Why does the book dismiss writing biographies of many saints as 'one-sided' when it seems like a valid form of public and spiritual service?

The Preface, in Chapter 0, directly addresses this perspective. While it concedes that writing the biographies of many saints is indeed a form of Guru service that yields spiritual fruits, it qualifies this service as 'one-sided or partial.' The author argues that relying solely on this method makes it 'difficult, or rather impossible, to attain the ultimate spiritual goal.' According to the text, the superior and 'most certain service' for attaining salvation is to focus on writing and regularly studying the biography of one's own Sadguru with unwavering devotion, as this specific practice is considered the most direct path.