Actually, I think what made a big difference is that Vane and Akali both got decent kill scores, and the fact that they had 2 supports and no tank, while your team was relatively balanced. Otherwise Varus would have carried his team, I imagine. Hard to say without seeing the Grid or better yet, watching the game. For all I know, WW was a rage-quitting, compulsive feeder (not saying he was), and Nami could never help but fall to Varus (not saying that was the case).
Also, as noted, you could have been easily stopped by any or all of them; but the fact that you can pubstomp by stacking cleavers doesn't mean that Riot needs to trash a decent item just because a number of people aren't thinking outside the box.