Chat honestly does more harm then good in league and it brings nothing to the game that you couldnt provide through smartpings or maybe custom flash timers. You can ping baron now or red/blue buff. the rest cant be communicated fast enough becasue you dont have time to chat in teamfight and people do what they think is right ANYWAYS (calling out targets isnt a chat only fearture either).
A valid argument is that you can "just" mute people, which is true. But then you cant see what they talk behind your back in all chat plus they will report you just out of grief
Chat is only ever active when concerning something negative, because when everything is going fine noone dares chatting since it might break moral or becasue there is no need to.
A lot of people dont know why all the toxicity is happening. toxicity comes from feeling like beeing treated unfairly. League doesnt allow you to just leave the game if you dont like your team. You cant get back at them without punishing yourself too. Reports dont do shit unless you submit a ticket for everything. So for the good of everyone just remoove chat from the game finally becasue its a tool to channel your anger directly after something went wrong in game. And since you will never be able to just leave the game without pentalty, maybe that would be a solution, like they do in korea. but without waiting for the game to end 10 minutes