Answer is they didn't: if the US buyer wanted it that badly they picked up the tab or otherwise they waited for the tariff to come down to 10% or went without. Also, very few goods in the US (probably none in the CPI representative basket of goods) are bought directly from Chinese vendors, they're bought from US retailers. Those US companies can eat the tariff cost if the exporter won't and they can't sell at a higher price. That obviously affects their margins, their sales and their hiring.
The argument is that “HN is turning into Reddit” has been said since the beginning of HN… but that doesn’t make it wrong. To me the transformation is already complete. Regression to the mean is unavoidable.