Perma chat ban

Why is there no permanent chat ban in league of legends? The way the system is set up now players who abuse chat eventually have their accounts permanently banned, but as soon as one gets banned they just make a new account and continue to chat abuse in dozens of games until they are banned once again. This makes no sense to me, riot could simply chat ban these players forever removing their ability to abuse chat. of course they could always make another account but they are more likely to continue playing on the leveled account and any game they play on an account that cant chat is a game where they are not abusing other members of the community. We all know there are a decent number of players with 10+ accounts that just make them over and over ban after ban simply because they cant help themselves. These players seep into unranked and low mmr games turning those places into pockets of extreme toxicity and riot's solution is to simply bump them down to a new account where they are free of all chat restricting penalties. This is not a solution, in fact it puts an unfair burden on the unranked and low mmr players that have to deal with these new accounts.

Permanently restricting the chat function would solve these problems. Most players who get constantly banned are banned for chat abuse, they lack the ability to censor themselves but they still want to play and im sure a lot of them are banned because they care about winning the game. So if given the option to keep their mmr/ rank and stay permanently chat banned I think a lot of them would simply not chat and continue to play/climb on their restricted account. That would mean less toxic players typing in chat and more players focusing on the game.

The only reason i see for not implementing a permanent chat ban is if riots objective is to punish these players in an attempt to make them reform. However at what expense? Is a player that's been banned 20 times going to change because of ban 21? Is it fair to stick toxic players on the unranked and low mmr community? Riot should make permanent chat bans a thing, I see this simple change as something that could drastically improve the quality of interaction for the whole community.