1. Yes - Housing is a problem. I think it is a salary problem. As tech corps in US earns money from the whole world, most Chinese tech corps can only attract Chinese customers. So the value generated from a same piece of code, is better in US. This makes US engineers' salary and status relatively higher in the society than those in China.
2. Yes - people are working 996. But I won't blame the law. I'd blame the culture, or the competitive nature of Chinese tech industry. Union doesn't do anything in China, but labour law does. It is written in favor of workers and executed properly, ask any entrepreneur in China. The problem is, I never seen anyone sued their employer. And there are a damn lot of people that actually working 996 voluntarily without asking by their boss, making the normal ones less competitive if they don't do this.
3. No, I don't agree here. - In tech companies of both countries, I found no difference, relationship does not matter that much even Chinese employees do have a closer personal relationship than US employees. And in other industries like finance, there are no difference either, b/c both countries are 'relation-oriented' in these industries.
4. Yes - I would not say its cruel tho. India, Korea, Singapore are all like this. Its just very competitive due to the limited educational resource and the amount of people who wants to use it. But yea I wouldn't send my child there (If I have one).
5. Pollutions - Sad, Beijing is not a human-habitable place anymore... Shanghai is still okay.
Again, I think the facts you provided are main reasons that stop people going back. Those in the article are slightly wrong(Github, VPN .etc) or not important(foreign business entry barrier) for individuals like me.