Great advice, I see player who constantly blame there team without looking at their own play first. Instead of trying to fix their mistakes they rather blame what happen to them on a mistake of someone else's.
Yes your teammates will make mistakes and yes it sucks that you don't have complete control over that. That's irrelevant though.
There is a lot you can do which counts as a mistake, "Top laner is getting ganked, you see it he doesn't you don't ping him to let him know, he dies you flame him"
What could of been done here the second you see a lane is getting ganked SPAM PING for him. that's your mistake and it could of saved him. Any small thing can be a mistake on your part