[T]he final written output is an educational product that ought to be built and tested around the needs of the reader, not the ego or indulgence of the writer.

[T]he final written output is an educational product that ought to be built and tested around the needs of the reader, not the ego or indulgence of the writer. Can you expand on this thought further? Who decides what the "needs of the reader" are, but readers themselves? And fiction isn't "an educational product."