What advantages and disadvantages were there in the ottoman practice of not making the eldest son the automatic heir of the reigning sultan?

The advantage of not making the eldest son the automatic heir to the throne is securing that the most capable and society supported candidate to the throne would win and lead the empire to economic and territorial growth. The disadvantage is that sultans often have many sons, therefore there were many rightful heirs to the throne which caused country to fall into civil war every time the new heir was chosen.