Why were the Jnaneshwari and Nath Bhagawat considered so important in Shirdi?

These books were considered paramount because Sai Baba himself designated them as essential for spiritual growth and salvation. Chapter 18 explains that the Bhagavad Gita and the Bhagavat were the 'two main books' and the 'essence of the Bhagavat religion' read daily by Jog. The commentary on the Gita, Jnaneshwari, and the eleventh Skandha of the Bhagavat (Nath Bhagawat) were described as 'Nath’s platform for the highest spiritual goal.' The text even suggests the dialogue between Krishna and Uddhava in the Nath Bhagawat is superior to the Krishna-Arjuna dialogue in the Bharata. Ultimately, the capable Sainath made it a daily practice for these divinely inspired books to be read to help his devotees attain God.