The Plague of AFK

The story goes like this... Here I am playing a nice game of ARAM on the Howling Abyss, everything is going great until I notice that one of my teammates (Wukong) is just chilling in the spawn point. I keep an eye on him and after a few minutes he begins playing. He continues to play until he dies, at which time he again respawns then just stands in the spawn vacantly for 2 or 3 minutes. This trend continues all game, which quickly adds up to a large chunk of the game spent with him just idling in the fountain. On top of this on a few occasions he just runs back behind our teams nearest tower and idles for 4 minutes. I play at least 3 games (mostly ARAM) a day, and often more, and I have noticed an epidemic of idlers, with nearly every game having at least one person who is obviously not prioritizing the game and therefor is idling for a few minutes every time they die or just at random points throughout the game. As far as I understand Leaverbuster the punishments it doles out are reserved for people who disconnect/leave/idle to the point of the system picking it up, but it seems to me that if you just idle for 3 or 4 minutes every few minutes of the game you can get by under the radar. This is very negatively affecting my games because although I report these people every time, the proliferation of this makes me feel like it isn't having an effect. Can you clarify this for me riot?

(Edit) This problem is rampant mainly in ARAM, I do play normals occasionally and have not noticed this problem there.