What is the purpose of great souls like Sai Baba incarnating on Earth if they are beyond birth and death?

According to the teachings in Chapter 43, the incarnation of great souls like Sai Baba has a singular, selfless purpose: the welfare and protection of devotees. The text explains that they 'take various avatars' with the 'sole desire for the welfare of devotees.' They are described as being 'gathered by the past merits of devotees' and appearing in a physical form to help them. Chapter 43 states that the 'rise of such Great Souls has the welfare of people as its purpose.' Once their specific task for the devotees is complete, they do not die but simply merge back into their true, unmanifest form, having fulfilled their compassionate mission.