Why did Hittite scribes use Akkadian in treaties and international correspondence?

Hittite scribes used Akkadian for treaties and international correspondence because it served as the lingua franca of the Middle East during the 2nd millennium BCE.123

As the established diplomatic language of the era, Akkadian facilitated communication between diverse powers, such as the Hittite Empire and ancient Egypt, even though it was not the native language of either party. Because of its status as a universal medium for written interaction, proficiency in Akkadian was a required component of the curriculum for qualified scribes working in the Hittite capital of Hattusa.31