I think the Chinese gov’t is doing the only sensible thing, which is to isolate the only city where most people are already infected. China being a dictatorship can do things like that even if situations which are not that serious.
Keep in mind China is still a poor and overcrowded country. That makes it easier for contagious diseases to spread. I have never been to mainland China but have heard the sanitary conditions are not so great. Only places I have visited in SE Asia are Hong Kong, Singapore, Thailand and Vietnam. Singapore was amazingly modern, Hong Kong is modern but really crowded. Thailand & Vietnam have lot of poor people. If I was dictator of China, I would do the same thing...shut off the one city where most infections have occurred.
All of that is true, but my point (relative to the apparent importance of this event to the Chinese) is that they could have (and perhaps should have) quarantined a huge city and built thousands of emergency hospital rooms in the past, they’ve never done it in any of the very significant prior contagious outbreaks.