You're confusing time zones with daylight savings. Time zones exist so that the same part of the solar day has approximately the same time associated with it wherever you are in the world (prior to the railroads, that was the only time - local time). So I can say "it's 4am in China" and you'll know it's the middle of the night without having to consult Google. They can also achieve the opposite, keeping neighbours on the same time when their solar days are actually different, e.g. within China. Sometimes that's useful.
Daylight savings exist for saving power (and were introduced in the war to do just this), providing more daylight hours for school children, and longer days for agriculture (now historic). There is debate about whether any of those reasons are actually valid.
The fact that you just said this, in this context, shows me how clearly embedded the AM/PM 'standard' is for people. Though that doesn't mean it's still a good idea to use it for meetings. It just signals to me that the only way of displacing this imprecise messy standard is to teach people to schedule meetings differently; and to have their smartphones display both the AM/PM time, and the standard meetings time.
Unfortunately that would probably still be as a 'timezone', and if we're doing that it may as well just be UTC since every timezone library I've every used already has that and best of all is only off by a few seconds at most without updates. (Close enough for applications that care about timezones instead of leap seconds.)
Daylight savings exist for saving power (and were introduced in the war to do just this), providing more daylight hours for school children, and longer days for agriculture (now historic). There is debate about whether any of those reasons are actually valid.