Idea for lowering toxicity
How about making surrendering easier and quicker to be available.
Being in a game with trolls/losing heavily only makes people irritated, being trapped in this situation until at least 20 minutes, provided the vast majority of your team even allows the surrender, can only serve to make people further irritated.
These people would be irritated and probably go start another game, carrying over that negativity. It's not just going to magically go away in the 10 minutes between games, especially if these games happen a few times in one day.
"But one time, the team wanted to surrender, me and another guy said no and we totally came back to win it!" That's fine for you but you're forgetting about all those other times that big losses turned into even bigger losses and people started becoming irritated with each other started becoming toxic.
I still don't understand why 2 people can out-voice 3, and why abstaining votes are counted as no votes, rather then the vote being out of 4, just terrible Riot logic.