What about when it's 1 or 2 towers down on every lane, 1 person is afk or quit, and it's 3/9 for one team to the other.
And it's very rare to come back after the gold different has been set up from 3/9, due to the difficulty, and the level of play it took to set up the kdr difference. A majority of games end up a long wait for an obvious result. A 10 minute surrender time still seems like a good idea.
Even if it's possible to come back, it's very unlikely. So what KDR is needed to say there is no possible way of victory? Pro games aside, most normal games are decided by 15 minutes unless it's pretty even the whole way.