To People Complaining About AFKs... You are missing the CORE ISSUE
The issue isn't that people are getting away with going AFK. Even if the AFK report system worked the problem would still be there.
If you can't stay at fountain without getting banned, players will just passively walk laps, go to other lanes, buy troll items, steal your JG camps, softly int, etc... none of which will count as AFK, but it is just as bad.
The Core Issue IMO is that players so often WANT to go AFK.
Whether its justified or not, it happens often. If I had to guess the main cause, I would blame the matchmaking for causing frustrating "unfair" games, and the games feeling like "teammate dicerolls" too often.
I understand everyone dislikes AFKs and that it isn't justified as a general rule, but clearly the players going AFK don't give a fuck. I'm sure if you asked the players deliberately going AFK they would all feel justified and wouldn't feel any remorse. In fact many would probably say they enjoyed it, as it gives them a feeling of control and justice that League matchmaking tries to beat out of you.
I'm playing the devil's advocate here, but my point is that to the deliberate AFKers, in their mind the AFK is a defensive reaction to something, a counter punch. If someone cuts you off in traffic, you honk your horn. What do you do if someone does the League of Legends equivalent of pissing in your cornflakes? You aren't allowed to speak your mind, you can't report troll stuff, you can't 1v9 anymore. So I guess what I am saying is, what exactly did you expect, Riot?
If I'm playing pick up basketball and some kid just keeps punting the ball out of the court, either the players will kick him out or I will go find a better game. In League of Legends if someone does the equivalent of "punting the ball", you're expected to pretend it didn't happen and just suffer in a 15-40 minute game that people play in their spare time for fun.