It's loser thinking. To scapegoat a teammate especially in a game and situation where there a ton of failed moments and poor decisions that collectively led to the loss. The difference to athletes is that they're in the games and the lockerrooms and play collectively to win games. I think that has been a great strength of Tippett in building a sense of team, brotherhood and resiliency. Pro athletes take mistakes in stride, knowing their own play isn't perfect, and why we get the cliche about parking a game and looking ahead. Anyone pro athlete in a team sport that outs a teammate and scapegoats those he or she goes into battle with will not survive long. There is no infallible athlete or person. Play as a team, win or lose as a team. Simple but fundamental premise if you're going to play a team sport. But essential when you are an elite athlete. Loser thinking won't cut it when you've beat Darwinism, and the thousands upon thousands that play said team sport, to make it to the peak.
EDIT: on the play you've fixated on, we see how awful Ethan Bear feels at his own accountability on the fluke goal given up. He's got two reasons to be pissed at himself. Shit happens, bad breakdowns on several fronts. But hardly defining on a sloppy, penalty filled game which had many turning points.