The whole point of surrending is because....you surrender. Why would you want to stay longer? You gave up right? And its fair if you sit out to long it boots you, if they are gone for 3 rounds then they obviously arent there and shouldnt get a higher place than someone who is.

The booting helps you more than you appriciate. Let's say you do leave, or just lag out and can't get back on for the life of you. It prevents people from milking all of your diamonds away from you. Besides the autoflag has always been there.