Right. Time exists. Our measurement of time is, at least somewhat, arbitrary.I didn't think that was the point though. The point I got from that was that how we choose to meter time is a social construct. How we choose to make time consistent across a globe
is time zones. There doesn't have to be 24 equal parts in one rotation of the earth. There doesn't have to be time zones. Humans didn't make time. But they did make up how to meter it.
Apparently, dividing the day into 24 measurement units comes from the ancient Egyptians, who divided daylight into 10 parts, added 1 part each for dawn and dusk, and then divided night into 12 parts based on the movement of the stars.
I assume that further dividing the globe into 24 time zones logically derives from the resulting, universally accepted division of the day/night cycle into 24 parts.