AFKs are so common and you don't feel like anything happens when you report.
Today I got around 5, yes 5, afks in my games, only one of them I won. afks pretty much decide if you lose or win since the disadvantage is too hard to overcome most of the time. I usually report the afk, but do you really feel like anything happened? I think you should get a notification along the lines of "Your report has been read and (summoner name) has been banned for x days. This way it will feel satisfying knowing the person that caused you to waste 20-30 minutes of your day has been punished.