I don't really care why you went AFK. I'll report you anyways.

I don't care if your kid had a nightmare, I don't care if your house burned down, I don't care if your cat knocked over a row of glasses, I don't care if you've got a stomach bug and couldn't hold it anymore. I'm gonna report you.

I do this because, well, if this doesn't happen frequently, it shouldn't be an issue. If this DOES happen frequently, then you deserve the ban because you shouldn't be playing at those times since you can't commit to a full game.

Sorry if it sounds cold or harsh, but this is a team game above all else. If you leave, you just ruined the game for 9 other people.

It doesn't matter your excuse or how important / urgent the matter was that you had to attend to - the fact is that:
1) It's the internet and there is no way to prove you actually had an emergency or you are just a kid with poor time management
2) You still ruined gameplay for 9 other players regardless of reason
3) It is your responsibility. If you can't set aside 1 hour to finish a game, then maybe League of Legends isn't the game for you. Real life takes precedent over games - if you aren't mature enough to realize this, then Riot is doing this for you by banning you.

If you cannot complete games and your forced to leave/afk games, then yes, you cannot play League of Legends.