Fresh new tip, straight off the presses!

Flaming your teammates for not playing well does not make them play better. Even if they are feeding, don't flame them in chat you will just manage to make them feed more and give up on the game.

What I do, on the receiving side is ask how people are doing. I'm raging on my side ofc, quite audibly in fact, but I don't let them know. Always try to be good to your teammates if you plan on winning.

And there is the mute button, so you can make that excuse, but if your teammate has to mute you because you aren't helping them to play better than you are no better than they are for feeding. A chain is only as strong as its weakest link, remember that. So it's better to make sure every link is moderately strong than just one (unless of course that link is the adc and you have enough peel for them).