Use your advantage to help losing lanes or you're not doing anything to contribute AKA you lose.
Having 1 person fed isn't going to do a whole lot unless they make up for the power imbalance instead of farming more stuff.
Like, I get my team fed, push my turret like 2 times, push other lanes to inhib and stuff, then when I return to my lane our mid and top turrets are pushed to nexus, I am like wtf.

It's like they planned out the winner, suspicious.