Come on, you can play a huge map for up to 10 hours while sitting in front of the screen. If you play every battle manually, you'll go crazy!
No, of course, I understand that if the enemy has 10 peasants and you have 100 angels, then yes, there's no point in fighting manually.
But when there's a chance of losing part of your army due to artificial stupidity, it's better to take control of the situation.