Can a Rioter comment on why this has not already been done? I'm sure it's been tossed around in a discussion before.
No rioter is required, because the reason is obvious:
#ABUSING THE SYSTEM.
You may think of this place as a nice fantasy land, where people are itching to help each other out.
Well, here are news for you: You are wrong. Most actual human bings are selfish, driven by greed, avarice and ego, and unwilling to do anything for a stranger if there is nothing in it for them.
So, you would have to hand out rewards, otherwise the system would starve to death.
Rewards for things done by anonymous persons on the internet ALWAYS means: Clever Bastards will invent ways to abuse the system to reap a maximum of rewards, with a minimum of, or no effort being put in.
Just an example how bad this can get: In the good old says when the great sh*t tribunal was still in place, riot used to give IP for participating, IF your verdict was the same as that of a majority on a given case. So, what happened? People wen't "fk it, I want IP!", and voted guilty ON EVERY SINGLE CASE, because there was statistically a higher chance of cases being punished than not. That lead to a metric sh*tton of punished people who had literally done nothing wrong, and forced Riot to shut its nice garbage system of handing out IP-for-"justice" down.
Now, could you design the system in a way to prevent that? Yes, you could. With a huge pile of ressources, and constant supervising on the part of Riot invested into it. And at that point, the cost simply outweigh the basically non-existent benefit.
Also, if new players want to learn the ropes, there are PETABYTE of instructional vids and written guides out there.