The inbalanced punishment scale...

TL DR; Yes, I know i somewhat did something wrong. That's not the main point! The main point is that I feel the punishment scale is inbalanced as hell.

Played a game today and at the 1 minut mark our adc/marksman says "GtG" and leaves the game, he havn't even bought a single item and is still at fountain, so we're already down to 4vs5. I tryed to play but got zoned and was camped, Since bot was 1vs2 our jungler coulnd't do anything at all about it.

At the 20 minut mark team started a surrender vote but 2 premades voted no. Even do enemy team had 7/2 3/1. On top of that 1 dragon buff and 2 turrets down to our 0 dragons and 0 turrets, all in all ~7k headstart. At that moment I was only 0/1 but underfarmed again since quinn zoned me and eve camped me. Now I decided to instead of simply afk until team lose or team agree to surrender I go and feed them a bit more so we could end this lost cause faster. I admit that I feed for ~10 out of 30 min!

So to the "fun" part: After the game I get hit with 2 weeks of ban, can't play co-op vs ai or even solo game in custom game vs bots? What does our afk Draven get? MAYBE +10min quee time for 5 games but that's one hell of big maybe.

So my question is: Why do I get so hard punished for 10min of "ruining a game", that's one (1) game!, when draven gets nothing for 30min of "ruining a game" and is the soul reason for my reaction? I can't have one bad game/bad day?! It's feels like if I would j-walk and get life in prision but he murder someone and only get a writen warning from the police.

Or do riot really promote people to go afk in games like this one? I mean, they don't get punished so why not? Force my "teammates" to play 3vs5? Is that really the leason you want me to leave with?