Trade is usually 'win win'. So when there's less trade, there's less 'winning' on both sides.
Imagine if Chia is the sole source of Silk, and the US is the sole source of Rubber.
If the US 'wins' a trade war with China by doing more damage to then, but there is less trade ... well then there is unmet/latent demand in the US for Silk and in China for Rubber that is not met, which is an economic loss.
That said - trade needs to be in fair terms or it doesn't work. If one side cheats, they can suck all of the 'win' out of the 'win win' for themselves.
Trade is usually 'win win'. So when there's less trade, there's less 'winning' on both sides.
Imagine if Chia is the sole source of Silk, and the US is the sole source of Rubber.
If the US 'wins' a trade war with China by doing more damage to then, but there is less trade ... well then there is unmet/latent demand in the US for Silk and in China for Rubber that is not met, which is an economic loss.
That said - trade needs to be in fair terms or it doesn't work. If one side cheats, they can suck all of the 'win' out of the 'win win' for themselves.