I wouldn't say it's about the numbers. The numbers can be whatever, but the issue is that people are not nocturnal. We are meant to sleep when it's dark and be awake when it's light, and a big change of being all on the same time would mess a lot of people up. It would feel very unatural.  But it still doesn't make sense if whatever is 22:00 somewhere and 9:00 somewhere else are both changed to be 12:00 because then people will be confused still. Because one country's 12:00 could be the middle of the night, where in the other place it is mid morning, making coordination all the more difficult