Riot Should Reward good behavior more often
I took a first year college class in psychology and my sister has her bachelors of art in behavior analysis; she has taught me a lot about it. One thing I have learned (with over 7 years of experience at summer camps too) is that rewarding good behavior produces overall better behavior patterns rather than punishing/threatening negative behavior.
With the tribunal and the constant threats of banning, behavior has improved slightly in League, but there will be a drastic change in better behavior if Riot continues to reward the good behavior. When the badges of teamwork, friendly, etc. came out, I saw a big change in behavior for a little while. Unfortunately, Riot made it a lot harder to get them after pretty much everyone got them because everyone was handing them out like candy. Now I see pretty much 1 in 100 games of someone with a badge. If riot were to give, lets say theoretically, a mystery gift, or 500 RP or something small like that per month under certain qualifications, people would change their behavior more-so than with the threat of banning/tribunal.
These conditions can be: Not receiving ANY sort of mute/ranked restriction or ban. Not being under leaver buster due to AFK. Receiving a certain amount of honor (this one is questionable). Of course, you would have to participate in a certain amount of games to recieve this as it would be too easy to just play one game a week without saying anything and receive your reward.
I am willing to guarantee that there will be a lot less negative behavior in League if something like this was implemented on a regular basis. I would for sure shut my mouth knowing I have the chance of getting a free skin, or RP at the end of the month. Of course, there will still be a lot of negative behavior, but not nearly as much, and it will single out the constant debbie downers, rather than the frustrated-once-every-10-games person.