Obviously there is enough blame to go around. But I feel the US companies deserve more blame. I believe ultimately, the responsibility lies with US companies.
When I purchase a product, I'm initiating a deal with the company on the label. They are providing me with a product that should be free of defect and performs the function it is designed to. When buying the product, I shouldn't need to know or care what channels it took for the product to get to the store. If it doesn't work, it is the US company who has broken it's bond with me.
Obviously, the Chinese companies did not fulfill their side of the bargain, but again, I feel it is the responsibility of the US company to provide a product that they KNOW is a good product, not assume it is good.
I had a friend who once worked for an Korean company that provided an American company with products. Many of these products were manufactured in China. I realized his biggest headache was making sure the Chinese factory delivered the quality products it was supposed to deliver. They could manufacture good products, he said, but they were always trying to save money, and if you didn't keep up with them, then they would try to slip in an inferior product.
I think these US companies didn't understand that, they didn't enforce their quality standards. Then they didn't test the product they received in a thorough way. Then, they sold it to an unsuspecting public. The blame should go to the American companies.