What was the advantage of a tetrarchy the form of government Diocletian created when he came into power?

It made the empire easier to manage because responsibilities were divided among four people.

The creation of the tetrarchy followed the Crisis of the Third Century. This was a period of military anarchy in which military commanders were hailed as emperors by their own troops and were then challenged by other commanders who were hailed as emperors by their own troops. Many emperors were murdered, sometimes even by their own troops who had elevated them as emperors because they did not want to fight a civil war.

Diocletian realised that one man could not rule the empire alone. He shared power with Maximian, who he made his co-emperor. The former took charge of the east and the latter was in charge of the west. Diocletian then created two junior emperors (Caesar), Constantius and Galerius. Diocletian and Maximian became senior emperor (Augustusti). Constantius was appointed because of the need to suppress a rebellion in Britannia and northern Gaul. The junior emperors were given the task of defending the frontiers along the rivers Rhine and Danube respectively, which were vulnerable to attacks. Therefore, another aspect of the tetrarchy was the improvement of the defence of the frontiers of the empire.