I'm not sure how bad EU region is with that so I can't tell whether NA is worse or better. But NA is pretty bad as it goes. Same for Korea. This game is just very toxic. And yeah a lot of it is attributed to people acting like bumbling moronic child but part of it goes on Riot. There are plenty of games that explores open communication and even voice comms with your teammates. And in those games, you equally get the same type of toxic and immature children or adults who just want to watch the world burn. However, ironically these toxic kids don't bother me as much in CS or other mmo games that would otherwise invoke the same type of frustrations in this game. Why? People make use of the mute/block functions. People in league don't; or they do but they use it in toxic forms.
Part of toxicity is your response to it. If someone is raging at me, I can't stop that. Me arguing back or even trying to explain to myself even if I'm 100% right and they are 100% wrong will make the situation worse. Again the issue is Riot's fault. They made a "safe haven" where you can't trash talk anyone or you get banned. Like I know dunkey is toxic but he brought it up perfectly. league became this fake ass game where it's like "Come have fun! Play with your friends! Enjoy a game with nice people!" But none of that is really true. If you try to play SERIOUSLY with friends, some kids end up getting mad and start arguing. It's not a good idea to play with friends unless they are impervious to anger and lashing out. This same problem happens in CS and other games too but the problem is almost never as bad. In League, Riot provided this haven for these pissant kids so they just don't stop and love to argue. Now you gotta watch out if you're ctrl 4 or showing mastery icon because people take that as toxic. Like seriously? LOL Riot is doing nothing but making toxicity worse.
Back in season 2-4, honestly toxicity IMO wasn't this bad. It's just getting worse. The problem is all the people who handled toxicity the right way (mute, ignore, move on; don't even bother reporting) all quit or left. Back then most people said "Stop crying about toxic players; just mute them and move on. It's only bothering you this much that you have to rage about it to random forum members because you can't move on/ignore these things." The basis of the idea was that in life, a lot of things are going to bother you. If you brick up and just start arguing back and defending yourself and display acts of toxicity or can't deflect toxicity targeted towards you, you're not going to have a fun life. There's plenty of instances where people will insult you or make fun of you or SOMETHING and you can't do anything about it (like when driving). The person who gets baited into being frustrated is the one who loses and gets into a car accident. Riot doesn't understand that. They think if we provide a safe haven for all these frail weak minded people, they won't commit suicide and they won't be depressed and they'll be happy. But that's not it. When people are depressed and the like, they feel cornered and they are usually out of their element. They are used to this phony society where eveyrone goes "HEY HOW ARE YOU" "GOOD HOW ARE YOU" in a high pitch voice which we all know is fake and devoid of real personality.
tldr; You're supposed to provide a strong environment to help these people get stronger. Look at how military trains its infantry. Not only do they challenge them physically until they are exhausted, they make sure they are beaten out of shape so they are mentally exhausted. This way they haev higher chance of functioning better as a unit and soldier/marine when they have no food, morale is low, etc. You can't expect a person to be strong or mature if you treat everyone in standards based on immaturity. Like you don't get jacked and built by staying home all day, you do it by going to the gym or working out. Riot's babying and all-seeing eye enforcement of toxicity is creating a MORE toxic environment because people are hypersensitive and on edge. And since most of them does not know how to react to toxicity, they just lash out and spread toxicity rather than sit back, reflect on the situation, assess, and move on.