Actually, you just went into detail explaining why it's a good idea.
In chess you'll see one player or the other reach over and lay their king over. It's an admission that, while the game isn't technically done, it's unwinnnable. So out of respect for time they simply acknowledge the loss and move on.
If, as you say, most losses see someone use a token, great! That's the point. They use the token, everyone leaves the game. It's done. The winners win, the losers lose.
Now imagine that you're playing and you're winning, but you're an asshole because you're smurfing. One of your teammates tosses out his token, you lose. Now also imagine this keeps happening because you're an asshole. It incentivizes you to stop being an asshole.
Imagine you're playing and 10 minutes in one of your teammates disconnects. Lets assume they're in a storm and the electricity went out. at minute 12, you use your token and move on. You weren't forced to play out a 30-40 minute game. You just moved on.
Imagine that game where your team is literally dying once/minute at minute ten. You just use your token and move on.
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The only real counter-argument to this is that it might affect people's ranks. People will have losses they may have otherwise won. Or wins that they might otherwise have lost.
This is true.
Do you know what else is true?
The game is riddled with smurfs. People will win or lose games by just being matched with a smurf.
The game has autofill. For those not aware, autofill means the game forces you to play a position you don't normally play. People will win or lose games due to nothing more than an algorithm making a decision.
The game has streamers who specialize in "bronze to challenger" streams. The people in those games will win or lose due to nothing more than matchmaking.
These are all basically random chance, and what they do is make the error in the ELO system larger. Riot enforces autofill in the interests of short queues. It explicitly allows smurfs and streamers in the interests of marketing.
So Riot has already accepted the random wins and losses.
The question is, can we do it in a way that decreases player tension. The answer is yes.
This isn't about creating a perfect system. This is about the fact that the game currently has a ton of variability from imperfections due to Riot making compromises. The question is how can do it while giving the players more agency over themselves?
And I haven't even spoken about how BAD riot's matchmaking is. It's seriously bad.
I remember a game I had where I was forced bot lane by myself because my support never connected. For those not familiar with the game, this means I was playing in a 1v2.
And I got huge. I took over the game. And not because the opponents went diving under my turret (note: turrets will damage the opponent), but because I just straight up punished them for positioning mistakes and killed them. I legitimately pulled a double kill with first blood in a 1v2 with no jungler help.
In postgame chat, someone on the other team asked me if I was a smurf. Technically no, but I sure as hell was smurfing in that game. Riot's matchmaking should NEVER have placed me in that game.
The fact that it does adds even MORE variability. It gives more random wins and losses to players. It increases the error rate of ELO in the game.
The community has a common sentiment: 80% of the games you play you have no agency in whether you win or lose. You just have to accept it and move on. But 20% of the games you do have an effect and to climb you need to be more consistent so that you're winning in that 20%.
The point is this: The issues of uncontrolled wins and losses already exist in the current system. It's just you're also forced to stay in a game for another 20-30 minutes, and that just increases everyones frustration.