Why don't people use the report function in normals?

DISCLAIMER: THIS HAS NOTHING TO DO WITH RANKED, IT IS NOT ABOUT RANKED IN ANY WAY.

I don't understand why people don't use the report function in normal games. I understand that its not meant to be taken seriously, and that it isn't as strict as Ranked, but rules are still rules. Inting is inting, AFKing is AFKing, and griefing is griefing. So why do people just NOT report things? A team can have an Anivia that constantly walls her team off from escaping and gets them killed, and when the team says to have them reported for griefing, nobody does anything. One particular thing that happens far too often is a rage quit, a request to report, and then the classic "GGEZ THANKS DC NO REPORT" at the end of the game. Rules are always meant to be followed, even if it isn't ranked. It makes the game unfun for everybody who is just trying to relax and have fun when the people who are ruining games get to run around without getting any sort of punishment for breaking rules.