I feel bad for Challenger players
Nearly 40% of games, Challanger players don't feel like playing out because they are probably complete stompfests. They would rather sit through the somewhat long queue times then try to come back to a unwinnable game. My guess the only reason lower tiers aren't the same percentage are because people don't want to go through the whole game startup process again or people in way lower tiers honestly think they have a chance when its 28-3 with 9 turrets to none. I would think Riot would want to reduce surrender rates, not increase them, but at the current meta and what direction Riot wants to keep taking this game, I expect the rates to just increase. I bet with enough time, we'll have surrender times of 10 minutes and maybe ever surrender after the loading screen.