Denying the Chinese access to American-designed parts broadens the competitive landscape, by forcing them to compete not just on supply chain, integration, and software, but also on chip design, in order to maintain parity in a key technology area.

This is advantageous to the US, or at least it's not as obviously disadvantageous as national competition centered on, say, manufacturing.

The US is never going to compete seriously with China on bulk/commodity manufacturing. But I think that there is a sense that we might have more of a shot competing in very advanced manufacturing (actual die fabrication; the manufacturing of high-end machinery and tooling for such; etc.) and in microprocessor design. Thus it makes sense to try to deny to China the fruits of those industries.

I would assume that the machinery used in high-end fabrication is probably a logical next step, if it's not export-controlled for one reason or another already. (If it's not, some arm-twisting might be required to get the Europeans to play ball, since I think a lot of that stuff is also made in, or made with significant submodules from, the EU.)