Hey there friend!
Yup. It SUCKS when someone dips out of the game, leaving you in a 4v5. This problem is something that we've discussed a bunch, and this is one of the solutions we've considered.
Unfortunately, though, we've seen lots of different ways that players take advantage of this specific solution. For example: players make smurfs with the express purpose of being the account where it's "safe" to dodge. They pair up with their friends, and whoever is on the smurf gets the responsibility of AFKing whenever the game starts to look rough. (Some players already do this, but "I can save my friend's rank" is just another incentive to do it.)
You may be thinking, "Well that's such a fringe case. How often could that really happen?" More than you think.
Or, in the worst of cases: a team is losing, and one of the players is REALLY not okay with that. So they start to bully the weakest link (or the child, or the girl, or the person who instalocked their main...whoever seems like the best target). They make the game SO miserable for that player that they leave. Loss averted. No penalty.
It honestly happens. Some people can be really vicious when it comes to winning.
Like I said, we get that games suck when someone dips out. Yet our responsibility to players is not only correcting the problem, but minimizing unintended consequences. I could live with the first scenario playing out. But that second one is outright unacceptable to me.
Fighting AFKs (and the pains they cause) is a huge undertaking for us, and we've got several projects underway to help address the issue (some of which we talked about in our dev article). Maybe there is a world where we implement this specific version of that solve. But it will only be after we've thought through every alternative we can, and we've decided that this is the best route to take.
In the meantime, we appreciate you bearing with us and being patient. A fix can't come soon enough, but I promise it's on its way.
Hope this helps clarify it a bit *-fistbumps-*