I wholeheartedly agree with this plan. However, as some have mentioned, punishing early leavers might be too much. After all, I sometimes leave because a kid is out of bed, etc....
If they would give a 5 or 10 minute penalty "in search" for droppers, then it would not have any impact to you if you must leave the game because your kid is out of bed, or if someone must go to the toilet, etc. That would only punish them who leave because they think their teammates are noobs and who search a new game directly after they left the old game.