Yeah I don’t think it’s poor sportsmanship or a problem. In a well designed game its a feature.
If making sure all of you lose is a thing that is within my power then you are all motivated to not stomp me so hard that I choose to do that. You are motivated to leave me with enough hope that I might pull off a win that keeps me vested in trying. It’s the old Europe Balance of Power paradigm where “going to war” is the lose condition for everyone.
I built an element of this into Blood Red Sands actually. Since one way to earn points is to just fight people you are motivated to get into fights. But not so many fights that you take so much damage you can’t achieve your goal and get those points. But the player who takes the most damage get a big boost for next game.
So if ever the other players have made it absolutely impossible for me to claim my goal (I.e. win) I always have the nuclear option. Fight everyone until I’ve taken so much damage I can’t fight any more. Score those points for fighting, get the big bonus next game.
So everyone is motivated to keep me “in the game” enough to not do that.