Make Giving Up/"Mental AFK" a punishable offense.
I know this sounds kind of crazy, but I ask you to think back to the time when being "Unskilled" was a reportable offense. I'm finding the game right now to be extraordinarily more about who has a worse team than who has a better team. The game is naturally snowbally right now, with good reason. The idea is that the advantadge gained from gold allows you to carry the game. So if you find a way to earn a lot of gold, you have the potential to 1v9 and carry. This is healthy, considering that we are all here for "solo que". What is not healthy however, is how easy it is for one person to run around the map, and int every lane, handing that advantadge over to MY opponents for f r e e. Or, more realistically, walk into melee range as Xerath and die for $free.99 every single teamfight. I'm in relatively high elo myself (Diamond 4 100 lp currently), and I'm honestly disgusted with how frequent one player drags down an entire team TOO far to the point where it needs to be addressed. When I ask someone to play safely POLITELY, it's appalling to hear back from them "Nah." Whilst feeling the powerlessness of having to be on their team. I'll admit, that I see this kind of stuff around 4AM more often than ever, but sometimes that's when I feel like playing the game. I shouldn't have to bar myself from playing because essentially drunk idiots, or "mentally AFK players" are que'd.
Let me put it like this, if you SINGLE HANDEDLY cost 4 people a loss, after around 3-4 confirmed cases in one week, I believe you deserve to be temporarily banned and/or punished. The thing about Not Trying/"Mental AFK'ing" is that those players, in my experience, always reveal themselves, so it would not be a monumental task to shape up the community with this approach. If you are a Draven one trick, Draven gets banned and you CHOOSE to not dodge and Vayne, but you then decide that you simply cannot handle farming after losing first blood and you int until you're 5/13/9, while your mid laner and top laner are 14/8/7 and 11/5/8 respectively, then it is safe to say that you DECIDED that you would take that loss for your team and you deserve to be punished for it. This happened to me the other day and it really seemed like I should be able to do something about it, but I'm not. I have gotten a small handful of those "Player Report Feedback" messages, but NEVER for reporting someone as an intentional feeder. Not even when they truly run it down mid.
I'll play Devil's Advocate here and say that this would probably be a lot of power to hand over to the bad guys, as innocent people can get reported as not trying. But I honestly, truly believe that if Riot did the work needed and just GLANCED over the chat logs, they would EASILY reveal the nature of the players in each game. And it would be worth the investment of time and money, because it would drastically improve the experience of 4 out of 5 players in like 1 out of 10 games (thats 8% of all players btw.)