When you buy some products from another country, Information gap, language, time zone difference, working habit difference will makes work much difficulty. You need spend much energy to handle the works. At the same time, you will face more works, for example small payment, collecting samples, QA works, shipping arrange......
This happens to the company they buy many products more. Traditionally, we try to cooperate with a trade company. But trade company have many disadvantages. So we try to find real factory ourself. Then problems comes again in your works.
So you can find some company appoint some staff to China as buying branch, this bring much cost burden to the company.
China Office is like a bridge, which connect China side & your side to handle the problems from the time zone difference, language, information gape......
China Office likes a light shinning the business all in clear situation. You will never worry about your business.