Forcing these Foreign companies to use local equipment is the best way to support the local industry.
In a perfect world this would be the correct approach. Problem is
there is no local equipment to force foreign companies to use them!!!
The whole problem lies just in one thing: the risk of suddenly the US forbidding sale of ANY type of semiconductor to China. Yeah... yeah... yeah.... I am being paranoid, but... If the US really wanted to screw China, this would be the best approach. Yeah... I know they would also screw a number of their own companies, but this is not an impossible thought.
Forbidding Huawi, ZTE and other companies to buy chips has hurt companies. More TSMC than American ones, but American companies have also been affected.
At the end of the day, what really matters is that China can manufacture semiconductors,
PREFERABLY WITH LOCALIZED PROCESSES, but right now anything will do. If not, why is China buying all those billions and billions of dollars worth of foreign equipment in order to produce chips?
If Taiwan was willing to bring equipment to make their 2 billion dollars factory work, so much better. That is two billion dollars less China would need to spend.
Furthermore, two billion dollars factory is a drop of water in the ocean that China's needs represent. But once the equipment and the factory are up and running, there is no way they will leave China. And they would be secured in the territory.
SMEE will only be able tocope with China's needs years and years from now. In the meantime, the risk of a complete blocade exists.
My two cents.