My only concern is that this is only for the "victims", not the toxic player. Everyone has the option, ability, and quick access to mute another player. There are several factors such as pride (bad thing), tendency to make remark or have the last word (bad thing), and anger (bad thing) that prevent players to mute the source of an annoyance, though D=. I'm not sure this will help the toxic player either.
I wouldn't really want that, but that's me D=. I really would not want a system to block my own teammate's potentially useful communication ability (Yasuo, did Syndra use her ultimate?).
I do not stress out, get angry at people who are raging, or resent them in anyway...so I never mute players. I still communicate necessarily (which mean not "omg, why you queue jungle if you suck -.-?) the best I can without any attempt to patronize players (EX: when are you going to stop int so I can gank?), and I attempt to calm others down if I'm 100% sure I can by acknowledging the cause, their characteristics, and more.
It's my opinion, but I wish people learn to control their emotions and actions running on resentment instead xD. That's not what games are for, though!