"I Don't Like Your Tone" Said The Tone-Deaf Robot
In response to all the people confused by their genuine criticism being met with disciplinary action (and those crying 'it's your fault, you disgusting people!')- just a little reminder. There is NO human intervention required for a chat ban. Riot's Player Behavior team is not trained to read logs for context, they're trained to make you feel bad for wanting to enjoy their game. Your greatest chance of being perma-banned is if a Rioter doesn't like your off-meta pick when you play a game with them. In short: Riot is not invested in improving the community and making a great gameplay experience for everyone. They have their robot to mass-discipline on the cheap, and it's not a flawless system. They know that, but instead of clarifying their summoner's code in a way that would make them accountable for improving it, they keep it vague and refuse to acknowledge when players are punished for things outside the Code.
When you ask support what you did wrong, the answer will almost certainly be 'tone' or, in many cases, a copy-pasted text snippet that isn't remotely offensive when the context of the game is considered whatsoever. The real truth is that Riot's robot aggregates the chat logs of reported players for similarities, likely presenting those lists to a technician once in a while for parity checks, like a primitive neural network. There is no human intervention aside from making sure the data isn't corrupted or manipulated, if even that. Basically- if telling other players what to build, making objective calls, or calling out trolls regularly gets you reported by trolls, you WILL be punished for those behaviors, even if it's your first time doing them. Riot is OK with this.
TL;DR: Riot hates you for talking. Just don't.