I know these Feeders are annoying and I know there is not that much to do anything against that, but did you ever considered that YOU are the reason they feed? Let me explain:
Players play bad when they are on tilt. I think everybody can agree on that. Tilt can be achieved in many different ways, one of them is by beeing insulted by a teammate. When your teammate feeds First Blood, and/or happens to go 0/3/0 in the first 10 minutes, then saying that he is bad is not the right thing to do. When a player feeds a little bit in the early game, than he is a little bit upset. Maybe because his opponent plays an annoying champion to deal with, or he is just simply not satisfied with his own skill and performance. Either way, a player who feeds is not happy. When now someone like you goes up to them and trashtalks them, you are not helping. You are putting salt into the wound and you will mentally hurt that player. He was already on tilt, but because of you he tilts harder and harder. So the early 0/3/0 will increase to 0/11/0 at the 15 minute mark. You still don't realize what you've done and you are not stopping acting toxic towards that player.
I know you are going to argue with me, saying things like "well, that fkin feeder could just fkin mute me! whats the problem?!"
Just because they can mute you does not allow you to be toxic. And even though they eventually will mute you, the first insults you've already thrown at him caused enaugh damage to tilt him. Yes, he fed, but YOU are the reason for that. Not because the Feeder is bad, nor the opponent is better. No. Just YOU and YOUR toxicity is the reason why your teammates feed.
I hope you will realize the mistakes that you've done. I hope you will be less toxic and get less feeders this way.
Have a nice day <3