I would agree if someone giving up 5 kills to a Riven, Yi, Xin, [insert snowbally champ here]. before 5 minutes didn't mean anything... but it does. That person then has global pressure, any lane they appear in is either dead or is pushed back to base. 5 kills means they are unstoppable and can 2 shot you, unless of course you are equally fed. I try to rally the troops but when 1 person is just feeding hard, it becomes a 4v6 and when this happens early on in the game you lose so much more and can do nothing about it. Turrets are made of paper and shoot cotton balls, so they are no help against someone who is 5+ kills ahead of everyone. If you make it to mid game, you have a chance but only if they make a mistake because by then the enemy team has triple your kills and dragons.
Basically when someone feeds, 80% of the time its over. You can try to shot call, but this is Low Elo, no one is going to listen. You can try to split, you can kill the carries, you can take objectives, but ultimately unless you can 1v5 and take all objectives by yourself, chances are high you lost at 5-10 minutes.
Not saying I am Challenger, I probably belong in Silver, what I am saying is either majority of my teammates need to be dropped to Bronze or let me rise out of this garbage... Sometimes its me who loses the game for us, I end up giving away a few kills to someone I shouldn't have or I make a bad call that costs us. Sometimes you just lose, either their team comp was better or their judgment calls were better. However, the losses due to a teammate feeding to the point it seems intentionally or I have 1 or 2 AFK's or my teammates just flat out ignore my calls, vastly out number my "legitimate" losses. I pride myself on my ability to pick out which loss is which, I don't get angry or mad when I legit lose, im upset i didnt play better obviously but there is no frustration at the game. The games where there was never a chance and it seems like it was just pure chance i happen to get the feeder instead of the enemy team, that is where the frustration comes from.