The issue is that people don't know how to call people out the RIGHT way.
Ex: Mid is losing lane hard (like 0/6) 15 minutes in.
How most LoL players respond: "Go F*** yourself kid, you're trash. Just uninstall."
How you should respond: "Hey, sit back near tower and farm. We'll come help in a minute."
Calling someone out in a negative way never works and it never will. It only puts that one person in a bad mindset as well as yourself. You think that someone 0/6 doesn't know that they are having a bad game? Everyone has bad games.
In reference to trolls, try to help them out in a positive way (build tips, strategy advice, etc.) and if they respond negatively, hit the mute button. This way, at least you tried to help out (it is a team game after all) and by muting them instead of responding back to their negativity, you can focus on your game instead of sitting there back and forth with someone that can't be reasoned with.