Phiggs88, that article makes it seem like foreign manufacturers are just now entering China to take advantage of their booming market. Nitto Denko, one of the first companies mentioned has 15 locations for manufacturing in China, including Shanghai, another 2 in Taiwan and 3 in Korea.
https://www.nitto.com/us/en/about_us/access/eastasia/

Sumitomo, the first company in the article is a more diversified company and I count 11 regional offices alone in China, so probably many more manufacturing sites there.
http://www.sumitomocorp.co.jp/english/company/point/easia/

Transportation charges, on-demand inventory delivery, Customs procedures and unreliable changing tariffs make having a local factory necessary to supply manufacturers.