You are correct - bone pointing and "singing" a person to death are mighty primitive.
I wonder if it is any more primitive than praying to help heal someone who is ill. In a general sense the basic mechanics are similar in that the faith of the people involved can have a great impact on the outcome.
In the case of prayer circles, faith that praying will work can buoy the spirits of the ill person, giving them strength and perhaps a belief that they can overcome. What would stop the opposite happening if the victim has faith that he can do naught but die as a result of the bone pointing?
