Why is League of Legends so cancerous?

When you start a match just type " /mute all " and then you'll only see pings from people, and wont have to see them being toxic. It's actually a really relaxing game when you just mute everyone and space out in your lane/jungle. I always play better that way too because then I can just think to myself and really focus on what I'm doing. -- At the end of the day its just toxic because its a team game and no one wants to admit that its their fault theyre stuck in low elo or that they lost a match (theres pretty much always a billion things you could have done better, and your decisions 5 minutes before can directly affect your teammates dying way later on in the match, etc)