“what time is it” is the natural way that people have asked about where in the typical day night cycle it is for eons. We don’t really have another way of formulating the question that flows naturally.
It would be the same time everywhere, but you’d only know what that meant in places you were familiar with. Otherwise you’d have to look up the difference in a big table, which is exactly what a timezone is.

We have a system for a uniform clock that’s synchronized everywhere on the planet. The people for whom it has benefits already use it.