Thing is, even with their current endless troubles, there is not a single foreign competitor with substantial scale on PC/Server CPUs (Intel), or the end-to-end networking/cloud/cybersecurity/DevOps IT backend that IBM can provide. And since China has no similar corporates of equivalent or larger scale, that US workers are 4x more productive is obvious - US workers are able to produce goods and services in scale, price, and reliability that simply have no foreign equivalent whatsoever.
even the EV/HSR/5G/nuclear comparisons fall flat because there - Tesla, Rivian, Wabtec, Westinghouse, Cisco/Mavenir/Ericsson US all are similar-ish items produced in the U.S.