Toxicity would be helped a lot by reducing match length and lowering power disparity from item leads
I've come to very strongly feel that toxicity would be helped significantly by Riot just completely reworking their match length and the power disparity that gold leads give. If matches were shorter so you didn't lose such a big chunk of time to a match, there'd be a lot less irritation and tension built up in the player. If gold leads didn't power spike people so high they can just nuke you with barely any effort, if you could have the match just be consistently equivalent and fair so that positioning and teamwork made the difference and not farming items or bloodsport kills, I think we'd see a LOT less frustration and anger in this game's playerbase.