The problem is players are more toxic than you think, and often I file more than 10 Reports a day because of toxicity, but I do agree players abuse the reporting system, in some games today where I was forced to play Jungle they rage because they Feed massively before even level 6 our mid laner gives up first blood, and feeds really hard totally unskilled, then they have the nerve to yell Troll because as a jungler its my decision on if a gank can actually be successful or not, my call was not to gank because they already fed, but rather group before the team feeds a lot more, and players get extremely hateful and toxic and file false reports for "Verbal Abuse" like honestly this is a problem because with the high report rate I am sure I will be restricted within this week very likely.
What Riot needs to do is get rid of the automated system and go to Manual Reviews if a player requests it and not only look at the player who was playing but take action against false reports. Being reported for verbal abuse simply because I can't gank a players lane and they want to argue in chat because I can't carry players who are bad.
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I still say we need "Role Selection" for Solo Q in ranked/draft matches it would help prevent a lot of toxicity.** Because one of the main problems leading to toxicity players who are not "Jungle Mains" or play differently than most in certain elo players rage when things go bad or game-play needs to be done differently, ( I would not have been reported in one of my games) if I would have not been playing jungle.
I also would not have had a toxic experience in two other games I got reported in as well if we had a role selection system because players wouldn't have been arguing about roles.
You are right there needs to be changes, and players who abuse the report system should be punished themselves, but there should be no limit to the number of reports filed, even in DOTA 2, a single game I run into toxic players abusing the report system there too, I get chat restricted for no reason there as well sometimes after one game of being reported while being called hateful things over the mic by others, and I report them next game if I am unlucky to get similar players I can't report them, and I don't file false reports unless there is actual abuse.
Sometimes in DOTA 2, I was lucky enough just like League to get players who were respectful, but honestly Solo Q over there is just as bad, and even worse if you get a restriction.