Why can't I play the game if I'm ahead or behind?

I can go 13 kills, which results in my team not doing anything. Or I can be behind, which results in me doing absolutely nothing in terms of damage or leaving my tower.

Going to have to blame snowballing and shutdown gold on this one. Jungler can help you; but he'll still take the shutdown 1k and I'll still be dying top/mid/bot etc.