Unpopular Opinion: Make it legal to leave after 5 deaths straight
I see no point to continue to play after getting unlucky in the lane. The snowball mechanic in the game makes it that if you lose your luck by misstep into a hook or JG camping you lose the lane entirely and no windows of opportunity of redemption.
People go against this saying that the entire team needs to function in order to win. However, if you are an important piece of the team (support, AOE bruiser, battlemage, etc) then you're probably bringing the whole team down. Unless if they give a boost toward players who have a low KD (which doesn't seem likely given the removal of catch up XP), it seems absolutely justified to make this change. Other players may say just to practice, which may not be applied simply because "We are having a bad day."