Why does toxicity matter so much in a game with a mute button?

I got permabanned for reasons i've come to terms with, but I don't understand the culture in this game anymore. Everyone used to flame each other and nobody cared because it's the internet and nobody gives a shit. Now people choose to report instead of just hitting a mute button. If someone is inting in a game and you get reported for flaming someone that is intentionally ruining your game and experience in riot's eyes you are in the wrong. I don't understand this as a player could mute you, and continue playing their game, whereas you can't mute someone inting. I don't understand how you expect this game to be competitive and not expect people to get pissed off and use the chat when someone is fucking up your time that you are spending trying to climb. For every game you lose you have to win 2 games in a row to get to the LP that you would be at to win that first. That means every time you are inted it basically takes an hour out of your life to make up for it. I guess I'm just confused when everyone started reporting and nobody started muting.