While you're not wrong with your main point, i just want to point out that i HATE when people talk about China city population statistics. Chongqing, for instance, has about the same population as London (~8 million) but someone (I'm guessing the patriotic wing of the Chinese census bureau) loves counting the entire municipality population when calculating how many people live in a city. For Chongqing, the 30 million figure is from an area literally the size of Scotland. If you look at Google Maps and overlay the proposed the city limits it's clear that they're massively inflated.
They've got a shitload of people and a shitload of megacities but this is often overlooked