His argument is that retailers are intercepting “the phone they bought” and preloading garbage on it and repackaging it before sending it to them. Maybe that’s something that happens a lot in China? If so, requiring registering on the Xiaomi website would be a pretty good way to thwart this.

In a way, it’s to protect naive users. And it still allows you to root the phone - go through this idiocy once and then never worry about it again.