Question about Obvious Intentional Feeding

So I just played 2 games in a row: The first was with one very obvious intentional feeder (literally quit after first death, came back, sold all items and proceeded to walk into the enemy team as many times as possible as long as they weren't afk in fountain). The 2nd was a Garen and Sol duo who just died again and again claiming they were trying but it was very obvious even to a new player that they weren't (walking up to the enemy Veigar and spamming taunt, hello?).

Why are they not banned immediately following the game? They just went out of their way to ruin an hour of my time (as well as 15 other people's) which could have been spent in another game but i said "hey lets play league and hope for the 10% chance at a decent game" (it is actually sad that i get a decent game 1/10 games, that is a matchmaking issue, nothing to do with this post). But yet all 3 accounts just walk into next game like it never happened? I guess I'm all for 2nd chances, but when you ruin someone's game literally just because reasons, you should be punished harshly for it. Something like a 2 day ban from anything but ARAM followed by a permanent ban the next time it happens. I know that sounds really harsh, but you know, if you are going to go out of your way to ruin 9 other people's time, you do not deserve to be in this community. I'm very curious about Riot's view on intentional feeding, because all 3 accounts are still out there playing games, when they just shouldn't be.