We didn't cut off anything. American companies would have been more than happy to continue offering products and services in the Chinese market.

The Chinese government didn't like that idea. They attacked American companies, stole the IP, and created their own analogs of American corporate offerings. If you are a company and are targeted by a totalitarian government, it's not unreasonable to pull out of that totalitarian government's jurisdiction.

Honestly, the American response to that was not nearly stout enough. Chinese goods and services had been sold in the US without issue for decades at that point, often to the detriment of both domestic and other international market players. When China was expected to play by those rules and allow American companies to do business in a mostly-unfettered way, they attacked the companies and drove them out of their market.