The Satcharita preface mentions writing biographies as a form of service. What are the specific limitations of this practice?

As detailed in Chapter 0, while writing biographies is considered a form of Guru service, it has significant limitations. Writing about worldly figures like politicians is a service limited by time and space, and because it is often rooted in self-interest, it does not yield eternal spiritual fruits. Even the more spiritual act of writing biographies of saints is described as being "one-sided or partial." The preface explicitly states that it is difficult, or rather impossible, to attain the ultimate spiritual goal merely through this type of writing, suggesting it is not a complete path in itself.