It seems absurd you would lose the full amount of ELO in games where people quit, or even more than one person quits. Why not just make THEM lose 30-40 rating or more and keep everyone on the losing team where they are at for the most part? It's pretty hard to win and keep ranking in a 3v5. I don't think it could really be abused for the fact that someone has to willingly lose 3 or 4 games worth of ELO just to drop and save their teams score, in a solo queue where for the most part no one really gets in a lot of games with people they know.