Just because we can mute you doesn't mean you aren't responsible.
I recently had a game as kayn jungle, and to make a long story short, we lost. A zed got big and he snowballed pretty hard. I don't really blame anyone in particular for the game's lost and only mention it because in said game bot lane had a problem. Our adc got pissed at our support and 10 mins in said "I ateh you blitz" The blitz proceeded to spend 20 mins ranting in all chat about how toxic his adc was. Our adc only said that one sentence. When I pointed this out he simply asked why I didn't mute him, then left before I could answer.
In fairness, I probably should have. But the issue was, IF I NEED TO MUTE YOU THEN YOU ARE DOING SOMETHING WRONG. And this extends beyond that small personal instance.
Muting is a last resort tool that you use to tolerate an otherwise annoying teammate/enemy for the duration of the game. It's a last resort, because it effectually cuts communication in a game where teamwork and communication are key to victory. Just because we can mute you at any time doesn't mean it should be used liberally.
[sg-ahri-3]