This word "toxic" is out of control
I'm going to submit that the word "toxic" has become the most toxic thing of all. Riot loves ambiguity, because it keeps them safe from being held responsible for continuity, so the word "toxic" that Riot (Lyte) loves to throw around hasn't been given an actual definition. There are very few clear cut rules when it comes to player behavior, and Lyte prefers to just deem anything considered toxic as toxic.
What this has created is a community of immature children (which is any online community) that use the word toxic to describe anything they don't like. Therefore, anytime anyone is asked to do anything, called out for a mistake, asked to fill a role, or any number of things they don't want to address, they simply call out the word toxic and they can continue being an unreasonable and unbearable teammate.
It's becoming as bad as the word racist. Whenever you're proven to be wrong or causing trouble, if you can just somehow, sorta kinda, make the other person seem racist, you're automatically right. That's how this community, under the leadership of Lyte, use the word toxic.
The result is that no one can actually communicate with their team because players hide their poor behavior behind the word toxic and feel justified by Riot for doing so. If i ask my top laner to ward so he stops feeding, all he has to do is call me toxic, and he can continue to feed because if I say anything else, I'm reported for toxic behavior.
As long as Riot perpetuates an atmosphere of reporting everyone with ambiguous rules, the community can only get more toxic.
tl;dr - The word toxic makes sure no communication can actually take place, and is used in every game by actual toxic players to hide their toxic behavior.