I have been playing League of Legends since Season 1. Through this time I have experienced all audiences of toxicity. From the early leveling to the higher echelons on Diamond it exists and continues to ruin the gaming experience for other players.
I commend Riot's rigorous efforts when it comes to combating toxic behavior, and I have absolutely seen a decline in recent years. However, I still observe toxic and unsportsmanlike behavior on a daily basis. Players that act in this way have a strong belief that their habitual behavior will continue to go unpunished because it has gone unpunished for so long.
I wonder why Riot does not invest in a Player Moderator System like other small companies have? Players who are not employed under Riot Games are offered a position of authority if their behavior has proven to be positive for an extended period of time. These player moderators are given a visible badge that makes other members of the community more inclined to play respectfully and behave.
I would like to reiterate that this question is not at all rhetorical, and I am perfectly open to the idea that this system would be horrible and ineffective for whatever reason. I would assume that some of this reasoning comes from the various moral arguments that contend that every player should have (and believe to have) an equal level of responsibility over reducing the level of toxicity on League of Legends. This, or that there is a greater level of confidence in the current system.