They are quitting the B2C e-commerce market, not the B2B market. B2C is an area where China is in many cases more advanced than the US, especially when it come

They are quitting the B2C e-commerce market, not the B2B market. B2C is an area where China is in many cases more advanced than the US, especially when it comes to mobile apps. US is more web app centric and China is more mobile app centric. China has really good apps like WeChat for which there doesn't exist an equivalent in the US. Also it does look like Amazon in general is putting more resources into it's higher margin businesses (eg AWS and Echo) than e-commerce.