Disclaimer: this is an opinion based thread, so no snowflakes in the comments. I may not be the nicest person in the world and i can sometimes act out in frustration in-game (of course i was one of those who were apart of the honour 2.0 ban-wave) but that's just being human, isn't it?
Alright so in a lot of your games especially if you're low elo you have run into someone who you like to label as toxic, correct? thought so. so i'd like to put my two cents into why people consider this game to have one of the most toxic communities to ever exist in gaming and i'm actually going to point my finger at Riot themselves that we have this problem and have had it for such a long time and here's why:
Because this is a competitive game and an E-Sport, players will take this game and the matches seriously and therefore will be more upset and frustrated when the match doesn't go according to plan, and i'm sure you have all experienced this at some point and that's fine because after all we're only human, we're not perfect, but this is where the problems arise.
So lets create 3 different categories for the "toxic" players, there is:
The Rager (which we just covered)
and The egotistical bootlicker
So the snowflake is your typical thin-skinned child-minded player who gets upset over the most mundane of comments either towards them or another player's mistakes. These people were brought up in a cottled millennial environment their entire lives and cannot handle any forms or criticism or anything deviant from a politically correct environment. now i'm sure a lot of people have to deal with these kinds of people on their day-to-day lives but it really starts to become a problem when they start leaking into our entertainment mediums, protected through some form of "affirmative action" which leads to my point that Riot's anti toxicity rules create more toxicity problems than they fix by giving snowflakes to ban those who get upset or frustrated within a competitive environment because they're incapable of growing a thicker skin.
Now onto the bootlickers themselves, so basically if the snowflakes were the trash mobs these would be the final boss. these sorts of people are the guys who typically parade their honour 5's that they just magically got one day because riot doesn't like us to appreciate our progress and actually believe they possess a moral high-ground because of that and basically preach their ""niceness"" in-game and like to call for mass reports on someone just for getting frustrated in a challenging, competitive environment.
tl;dr Riot's anti toxicity rules makes the game and it's community MORE toxic than it does going round solving any problems, because they obviously care more to foster thin-skinned snowflakes than to actually tackle community issues so no wonder that league of legends is regarded as one of the most toxic communities in existance.
I don't expect riot to make any changes to help combat "the most toxic game" tag branded onto the thigh of league of legends, because after all, they are based in california.