This ban system is a joke...
In this game, people who snap at a troll who goes around feeding their lane and call them out, maybe get angry and tell him to stop are more likely to get baned than the troll himself...
Seriously, RIOT, your whole system is a freaking joke. I reported 5 people who trolled ranked going 0/13 or even worse lately, and I just checked, all of them are STILL ALLOWED TO PLAY and PLAY RANKED!
But I bet if I would have called them Assholes, Jerks or Idiots, I would already be ranked and chat banned.