In reality, tariffs only harm the consumers of the country that imposes them.
Trade deficits aren't what most think they are since US$ going out to purchase foregin goods can only be used to purchase US goods or to investing in the US. There is no loss.
It's not that doc is doomsaying, it that she's doomsaying Trump's tariffs while defending Canadian and other countries' tariffs that Trump is reacting to.