Banned for one game that we won

I was just banned for intentional feeding. If you look at the game, yes that is kinda (100%) what happened early game. My premeades and I got mad at the 2 people who instant look bot lane. So we went ahead and did a old Tyler1 on them. This was, I admit fully, the wrong thing to do. No excuses here. But afterwards, we decided to actually go ahead and see how this game is gonna go. So we went and started playing for real. (before this the score was about 4/17 for the enemies). So we together sat down tried our best. And we did good, both yasuo and Irelia got quite many kills, and so did I, just not as many (hard to get kills when competing with a Yasuo and Irelia). After giving it our best, we managed to get ahead of the enemies and to win. We won, and it was almost completely our effort. My end score was 7/17/21, yasuo had 21/12/16 and Irelia had 16/18/10. Out of the 3 of us, I was the only one who got a suspension. When playing the game, I try to always be on my best behavior. We did something stupid, but then took the responsibility of it and overcame it, just for one of us to be banned afterwards

edit: I guess I didn't make the point clear on why I posted this. I do understand why I was banned, my point of confusion is more why only me, why not my other premades? Not that I want them to be banned, but their did the exact same thing and nothing happen to them.