i disagree the thing is theres no useless people in a game just the fact that your hold a wave pushing it can be a huge difference in a game
how ever i did see games where my entire team including me where doing terribly if we fought someone we died
and onlly that single yi top lane started roaming and easily kept on beating everyone he met
i also had a game not that long ago where i called jungle locked in jungle all of a sudden mid lane starts fighting and it becomes a duo mid lane
and last pick just locks jungle
so mid lane loses bot lane we had no bot lane i gave up on that game with that many trolls rammus folows around to smite all the monsters im fighting and is useless i can hadly get farm so im useless
riven top lane wins they cant even 3v1 him allowing me to get some farm sure i cleared some waves and sieged some towers but really that riven carried if he didnt win that i wouldnt even be able to get some farm
if you carried it doesnt mean the game aws 100% your work but probertly most of it like with a huge difference