I love LoL but I can't stand some of the people who play it. I don't know what it is about this game that attracts the worst people the internet has to offer. And when I say worst, I'm not exaggerating. I'm speaking as someone who played Counter-strike for years; someone who played TF2 on the 4-Chan server. So when I say the worst, know that I'm speaking from experience.
The worst.

I had an idea. A reputation system for LoL. Maybe it's a terrible idea so feel free to tell me if it is.

Everyone has a hidden reputation score. You don't know what yours is. High rep good, low rep bad.

Matchmaking is tweaked. Players with good rep are more likely to be matched with other players with good rep. Players with lousy rep are matched with other players with lousy rep.

Players who are cool (i.e. good sportsman, who take one for the team, who say glhf and mean it, etc.) are rewarded for being cool by being matched with other cool people. Rage-a-holics, trolls, and whiners are matched with other douchebags and play in a hellish fun-house mirror world where everyone is as awful as they are. In short, you get what you give.

What hurts your rep?
-When you report someone and it doesn't stick.
-When someone reports you and it does stick.
-When you report someone for unskill.
-When someone mutes you.

What boosts your rep?
-When someone requests to be on your buddy list.
-Offer a +rep button at end-game. Click it to give someone a boost. (Important note: there is no -rep button.)
-Every time you play, your rep goes up a little bit. If you are on good behavior, poor rep will heal with time. Anyone can escape bad rep hell.

Each little incident that +/- your rep is a drop in a bucket, but over time, those drops add up. You have to be consistently cool or consistently lousy for it to matter.

I can think of a dozen ways this could easily be abused.
For this to work, what improves/harms rep should be a RIOT secret. Everyone knows that rep exists, they just don't know how it's calculated. It's proprietary information, just like elo. If no one knows what the rules are, they can't be abused.

So... theoretically, this conversation should have never happened and by suggesting it you may have doomed it?
Yeah, I guess so. Quite a paradox.