Because they are AI bots and Blizzard has programmed them to always say that so that the player will feel good about themselves even if what they did served zero purpose or would actually work against anything but a bot. It’s designed to make you feel good so you keep playing. You can program a robot to thank you and say nice things about you when you torture it. It’s a computer it can’t think. If this is your argument then boy did Blizz program you well.