Kill Stealing Truths
Listen, read, comprehend. Kill stealing is a real term used to describe real events. This is a team based game. If you steal kills from your adc and you're the support that's not good. If you go to aid your adc in killing someone and the adc dies, you are not kill stealing. In fact they might not have been able to get the kill or the assist at all if it weren't for you. Kill Stealing is a bad thing when you go out of your way to do it. It causes the adc or carry to lose money and consequently lose the match for the team even if you are a carry of sorts.
However if you are helping a lane who got ganked and would be dying otherwise or does and then that person wants to get rageful just tell em Kill Secured and watch them get so mad they start dying and lose the game for the team.
Seriously. Get a better attitude about teamwork fundamentals and maybe LoL will have a community worth playing with.