A thought about toxicity
I've thought a bit about why I am toxic in games. (Only applies to ranked for me, but for others it could be normals and aram, and even bot games).
I think that some of it has to do with how we associate gameplay to other sports. If a guy misses a basket in a basketball game, things don't usually turn into an all out verbal brawl. Now some of that has to do with keyboard warrior mentality and not being afraid of anything because of anonymity but I also believe part of it has to do with how we treat machines/ single player games.
In a single player game if I die I get mad at whatever it was that caused me to die, especially if it seems unfair or too difficult. In a game, because we don't usually have voice chat, we see other champions as pieces that aren't behaving, like faulty programs, or for some, like people trying to lose. There's a disconnect that occurs where we behave using antisocial methods, like verbally abusing inanimate objects, and often when many things are going on around us in game and 4 people are variable components to the team that may or may not act according to logic you deem as default game logic, we take our anger out on them for not operating as we think they should have operated in that situation.
For instance, in a game where I control all the pieces, I might move the tank in first and follow up with a mage assassinating the ad carry and the support saving our ad carry from the other assassin. In game what really happens is I go in as a tank and my team stands under a tower and pings question marks at me and I die for nothing. In my mind it's their fault for not following through, but in their mind they did not trust me to shot call. (Especially apparent as the team tank because of the role of initiation).
When we don't speak to each other at all with voice communication, toxicity occurs as a response to "poor programming" which is really poor communication. For people like me who have trouble communicating and aren't very suave people (I'm a bit of a social reject who has always had a hard time expressing my intentions appropriately) it's very hard to constantly be the target of criticism because I can't seem to rally my team around my shot calls. That could of course mean I have terrible sense of when to go in. But I think part of it is I trust people to do what I envision them doing, and they don't do it because we think differently than each other.
I haven't dabbled in discord too much because of not owning a microphone yet, but when I was just listening to the other people talk, I "raged" less and had a more enjoyable game, win or lose. That's what made me believe a majority of this toxic environment stems from a lack of verbal communication, and a more programmy approach to the situation of having a teammate that's doing poorly or doesn't seem to follow up.
That's just my two cents.