Flex ranked premade team

Hello guys, i started to play the flex ranked on my main account and was surprised what kind of people were there, then i got the idea of playing on my silver smurf, and ooooooooooooooooh boy... i just played a Talon mid game, vs a full 5 man premade, and they were flaming each other. Why the hell... do people play premade... and still flame each other through all chat.... seriously, i dont get it, please explain this to me someone, please!