China’s using CST/UTC+8 and while there are variations from the west to the east for the time of day, that’s only a variation of 5 hours in the worst case. I’m flubbing the stats here a little but essentially your average is going to be within 2 hours of daylight differences which is your variance across seasons anyways.

What was being proposed was something throughout the world where someone’s morning could be another’s night. That’s a huge difference and not at all comparable.

Words have meaning because many people want to use them. I very much doubt people would adopt something like this within the same country much less worldwide. You could be right and that people might actually change but for something so drastic (and cultural even), I’m willing to bet few would bother.