20 minute queue time for going afk for a short period of time?

So, I was playing some unranked draft mode, when I was told I had to go help with dinner. I made my dinner in record time, and got back within 8 minutes, after which I basically carried my team as Aatrox jungle. Both teams in game were really nice, and no one was mad that I had to go afk. When I get back on, I find that I'm banned for 20 minutes for five matches! I got the five minutes five match ban once before (before I knew that there was a penalty for leaving games). In my opinion, this is ridiculous. Trading 8 minutes of wasted game time for 100 is not acceptable. So, even though this won't be read by Riot because that's how they roll, I think that it would make more sense if they balanced wait times for afk times (gone for 8 minutes= 8 minute queue per game), scaled wait times depending on the number of times you went afk or left (5 mins, 6 mins, 7/8/9/10, not 5 to 20), implement an afk forgiveness system (the five minute ban was 5 months ago!), or simply don't ban people for being afk for less than 10 minutes.

Not that my complaints matter to Riot.