This is the bind the US women are in, especially the BTC women. They are trained to be time triallers. Everything they do is designed to accomplish good times in even-paced races with a solid last mile. And they get very good results in TTs.
They then go to championship races where Kenyans and Ethiopians bounce the pace around so much. The sad thing is, I listened to a Curious podcast with Elise Cranny and she even said that was the hardest part of racing in Tokyo - they struggled with the changing pace lap-to-lap. And what have they done about it?
They could maximise their performance by doing as you said and trading off 70-72 second laps. This is what they are set up to do, it's what their training is directed towards. But yes, they would still get beat. They also don't want to lead.
So, that's their predicament: lead the race at a good pace, perform well and lose, or tuck in at the back, get run ragged by a yo-yoing pace and lose in a mediocre time.