IMO, the concept of sportsmanship is lost. What they did was painful to watch. For those that are the “score as much as you can and not give a damn”, I would just say that we all have our standards. Mine are traditional to the point that you do not embarrass an opponent if you can help it. As for the coach and staff, there is a way to hit the brakes, and not only did they not do that, they also celebrated like they just won the cup. So, in truth, the USWNT lost many supporters last night. I am one.
Again goal differential is a tie breaker, the other teams in the US Group may very well beat up on Thailand as well, so the rules in place dictate you have to try to score as many goals as possible, it keeps the game interesting even when the result is no longer in doubt.
And again, substitutions in soccer are limited, so you can’t just bring in a bunch of backups.
Now, if this was an elimination round match, where goal differential didn’t matter, then I would see your point.