Toxicity is a way to make money.
Toxic behavior is emotional behavior. To climb you need to give it your 200% and only be focused on improving, rejecting emotions if your other lanes feed. Naturally, some players will vent their emotions through the CHAT if they become tilted. The CHAT is an outlet for riot to make money, because to make money, you need the consumer (player) to willingly give up their account (ingame currency/ spent currency). Said player will be banned after, chat restrictions, and permaban if toxic behavior in CHAT continues.
Player will make a new account and spend money for exp boosts, champions, skins. Riot will make double revenue off the same person. Said player watches streamers, tries to consume lots of information on how to improve. Emotional behavior has nothing to do with gaining information on player skill improvement. Said player will at some point tilt again due to the inevitability that is league and vent his emotions through CHAT.
CHAT is the source of riot revenue from toxic behavior. Riot chat restricts but never permanently ban players from chat. Riot feeds on the guilt that players feel when they see "logs" of CHAT when they are banned. But never does riot permanently ban chat from a player. Because to willingly give into venting emotions via CHAT, gives riot a reason to ban player and make player spend more money on a new account.
Toxic behavior is neither shunned upon by riot nor promoted. Riot, a multi million dollar company, scams players who pay real money for ingame currency out of their accounts via guilt through CHAT before permanently banning the use of chat.
The cycle is to double, triple, quadruple revenue from a single consumer. Emotional behavior, while it can improve, does not relate to improving skill and knowledge of game.