By promoting reporting now a lot of the abuse has turned into threatening to report each other. Where before new players would be called shit. Now they are threatened for being bad. There is actually a report option for reporting a new player.. this makes many new players give up because they feel it is against the rules to have no idea what they are doing.
The Tribunal while a nice idea doesn't work. Riot's implementation has a rating system where judges are ranked based on their accuracy. That means many people punish based on what they think other people are doing instead of making their own decision. On each case there is no requirement to spend a specific time looking at it. No requirement to read all the text. I know people who punish every case without reading and run at 90% accuracy on the league table.
Another issue with the tribunal is that it punishes for almost anything. If you say GG after 9 minutes... its punishable. If end the game saying gg easy... its punishable. Combine this with the fact that enemies can report you without specifying a reason means a percentage of players who get punished shouldn't be in the tribunal to begin with. Combine this with terrible support... getting unpunished means going on Reddit and hoping a Riot employee spots it..
At best Riot have shifted the problem from verbal abuse to threatening to report. At worst they have failed completely.
The two main flash points are before you can play ranked games and have a new account. The second one is in champion select...
If you are banned you make a new account. If you want a second account you make a new account. This means the game for new players is incredibly toxic. About 50% of new players are people on smurf's or banned players leveling. This leads to a lot of frustration when you have a 20 death ally on your team. There are a bunch of things they could do.
1. Add a tip pointing out a mute button exists... It took me 80 games of randomly being shit on before someone told me about the mute button. If someone starts to spout abuse I just click the ignore button. Problem sorted.
2. They could give headstart smurf accounts to people who tick an option saying they are experienced players. This would help noobie players play against each other and have a soft intro to the game.
3. They could improve the tutorial so players actually start with some idea of what they are doing.
4. They could make the early climb on new accounts start versus bots to force people to actually get a feel for the game before throwing them into PvP
All 4 solutions would ease the problem new users are facing.
Another issue is in games where 2 or more people want to play the same position while picking champions. A lot of people say 'mid or feed'. They want the mid position. If they don't get it they will repeatedly let the enemy kill them in game...
Simple solutions...
1. Implement a dice in champion select to allow people to roll for the same position.
2. Simply add a line of text when people enter champion select that position is given in order. If you are first pick you have first pick of position. It is up to you if you want to give it up.
There isn't a single tip that says "if you ally is having a hard time in lane, consider aiding them rather than criticizing them."
The attitude of league at the moment is "if you playing bad you are spoiling my game and I will abuse / threaten to report you for it."
When you actually take the effort to communicate with your team and your team actually aids weaker players the mood in games greatly improves. The trouble is that Riot provides little guidance on doing this.
For all their research the implementations based on the research sucks.