If great souls like Sai Baba are beyond birth and death, what is the purpose of them taking on a physical body?

According to the wisdom shared in Chapter 43, the purpose is entirely selfless and centered on devotion. Saints incarnate with the 'sole desire for the welfare of devotees.' They are said to be 'gathered by the past merits of devotees' and appear in a physical form specifically for the sake of their protection and salvation. The text emphasizes that the rise of such Great Souls has the welfare of people as its fundamental purpose. Their physical body is just an adjunct, a temporary form for a specific task. Once that task is over, they merge back into their true, unmanifest state, but their presence and power remain to guide and awaken devotees.