Please realize that the "look at your kda" insult is not always valid
A lot of the times a players score doesn't represent what they provided in a game. A 1/5 yi (while is considered feeding) still can be considered to have done well if you look at how many dragons/turrets they took for your team. A 2/7 adc doesn't always represent their skill level, but how bad your team's frontline and peel are.
I wanted to contribute to these "Please realize" threads :3
Edit: I should also mention that if you have someone on your team that is 1/7 or something and have no excuse than ya, the insult is valid. It's just that some people are blind to other player's situations and should step back and look if what you are saying is actually valid or not.