AFAIK, an important reason eunuchs were preferred as generals and high officials is because a person who was castrated or had any other deformity could not be emperor (https://en.wikipedia.org/wiki/Political_mutilation_in_Byzant...) Exceptions did occur, e.g. Justinian II, but rare. It was also common practice to castrate sons of deposed emperors.
Comments
AFAIK, an important reason eunuchs were preferred as generals and high officials is because a person who was castrated or had any other deformity could not be emperor (https://en.wikipedia.org/wiki/Political_mutilation_in_Byzant...) Exceptions did occur, e.g. Justinian II, but rare. It was also common practice to castrate sons of deposed emperors.