The text compares Sai Baba to other saints like Gyaneshwar. What is the purpose of this comparison?

The comparison in Chapter 43 serves to illustrate the eternal and unbroken nature of enlightened beings. It points out that just as Maharaj Gyanoba (Gyaneshwar) gave darshan three centuries after his passing, and just as Nath Maharaj, Tukaram Maharaj, and Samarth Ramdas became enduring spiritual presences in their respective places, Sai Baba is the same for Shirdi. This establishes that Sai Baba is a beginningless and endless being who, despite leaving his physical form, will never fall into the danger of birth and death and will remain powerful and present even at the end of the universe.