Two can play the scorthed earth game... look at the ramifications of semiconductor shortages right now, then imagine TSMC in TW out of service...As previously mentioned, while there are former TSMC corporate officers working in SMIC, there is no assurance the same enthusiasm goes for the entire workforce.
It ain't like making hot wheels, lack of exacting diligence can ruin a whole batch. Complex and sophisticated end products are not something people can be forced/coerced into producing.
Making good chips are hard even without the complication of war, even gravitation deviations can ruin a batch of chips in peacetime.
Going back to my initial assertion, TSMC production line, workforce and IP are not a minor factor, at best.
Moores Law slowing/dying helps China catch up, but the world chips to standstill especially at the high end for the next half decade or more will certaintly buy China much more time...
As it is Huawei and other Chinese tip of the sword national campaigns are not have access to it anyway... time to literally level the playing field and spread some of the pain to the anglos too