I hate too when I hear the "Report X for feeding". It drives me up the wall. In my opinion feeding is not always intentional. Champions get fed through CS, killing other champions, monsters, towers, etc.
Only 'intentional' feeding should be reported, not because someone is having a bad day or is outplayed. Being outplayed is part of the game and learning from that helps one get better. Constructive advise works a lot better then raging. I have seen many games where one lane kept feeding, but late game they caught up and helped secure a victory. One game for example I feed 4 times as Mundo to an Olaf, finally we got a couple ganks on him and I was able to catch up on CS. Its all about working as a team and figuring out how to turn a losing situation around. When I am on teams where people rage that rarely happens, when I am on a team that works together, well, I have to say I have seen some remarkable turnarounds scaling into the late game.