If you've ever considered flying to China on a carrier that operates out if China, you may notice that your airline choices on many routes from the US are very restrictive. This isn't your imagination, this has to do with rules put in place by the Chinese government and how airlines operate to international destinations.
If you like Hainan Airlines for example, based out of Beijing, you might think it is a simple story of grabbing a flight from LAX to Beijing. After all Hainan is based out of Beijing, it would make sense that Hainan Airlines would fly this route directly... you'd be wrong. I ran a test case and Hainan's website will actually route you to Seattle on Alaska Airlines (partners with Alaska Airlines) before catching a direct flight to Beijing.
The Chinese government heavily restricts how China based airlines can operate internationally. Only one airline is allowed to operate any single route. This means that for Hainan, even though they are based in Beijing, they cannot operate the Los Angeles to Beijing flight, because a competitor already operates from LAX to PEK. Hainian, however, was able to grab the Beijing to Seattle route, meaning no other airlines in China are allowed to operate from Beijing directly to Seattle.
Honestly I'm not totally sure what the aim of the Chinese government is here. Maybe this is supposed to minimize competition between China based airlines so that one single airline is better able to capture traffic on that route when competing with US carriers. In reality though, this has forced Chinese airlines to come up with really odd routes that may not make financial sense, just to get around the Chinese rules. Often this means grabbing traffic from a high traffic airport like LAX that they want and sending it to a much smaller and less flown airport in China.
While this really has little impact on people outside of those that like flying Chinese carriers and those of us who want to try all different types of carriers for the experience. Many people living in the states are going to likely fly with Delta, American or United since these airlines allow us to connect from our home airports and then on to the Chinese city of our choice. This is merely an oddity of the Chinese airline industry, but it may just allow you to see cities in China you may not have ever thought to visit, and with no additional connections in China.