What are the limitations or drawbacks of writing biographies of worldly figures, as described in the source?

According to Chapter 0, writing biographies of worldly figures like parents and teachers is a form of Guru service, but it is of a worldly nature. Its importance and impact are considered temporary, limited by space and time, and not eternal. The text states that even if such writing contains public education and philanthropy, it is often rooted in self-interest. Consequently, this type of service does not yield spiritual fruits. Similarly, while writing the biographies of many saints is a form of Guru service that does yield some spiritual fruit, it is considered partial and insufficient for attaining the ultimate spiritual goal.