Try coordinating meetings around the world in cyberspace, you will quickly learn how confusing world time can be. The big problem is bloody Daylight Saving time which throws all international timing out of kilter several times a year.
Consider the relation between two cities, for example Melbourne, Australia, and Washington, USA. Let's start during Melbourne's spring when both cities are for a short time running on normal time. At this time Melbourne is 10 hours ahead of GMT (Greenwich Mean Time which is also known as UTC -- Universal Time Code -- just to add to the general confusion). Washington is 5 hours behind GMT. This means for people in Washington and Melbourne to arrange a meeting they must settle upon a time 15 hours apart. No great problem -- this can be arranged.
Now Melbourne starts on Daylight Saving time and puts all its clocks ahead one hour. Now if the people who are meeting weekly have arranged to go by Washington clocks, then the people in Washington continue to meet at the same time but Daylight Saving has made it appear to Melbournians that they now meet an hour later. Not a big problem, it will undoubtedly cause some small hiccups but no biggie. If the time for the meetings was set at GMT, then again no great problem, only those fools in Melbourne need worry about the apparent hour's shift in time for the meeting.
At the end of summer Melbourne comes off Daylight Saving time and goes back to sane time. The meeting times will apparently shift forward an hour, and will trip up a few people.
However, now a short time afterward, Washington will move to Daylight Saving time. If the meeting times are attuned to Washington clocks, then people in Melbourne will have to adjust their meeting calendars forward yet another hour at some point which is not likely to be announced in the antipodes. This will catch out lots of people. If, however, the meeting times are set to GMT then there will only be an adjustment by those in Washington beginning Daylight Saving time. Their meeting appointments will appear to them to shift back an hour at commencement of Daylight Saving time.
Later, of course, Washington will come off Daylight Saving time and either their meeting appointments shift if they are booked in accordance with GMT or Melbourne will have to alter its meeting times yet again (without knowing when Daylight Saving ends in Washington). This will stuff up some people in either Washington or Melbourne, whichever way it is done.
Then the whole ridiculous cycle repeats itself, with the time of the meetings changing 4 times in the year again.
If this wasn't so bad, consider what happens when you get other places which hold to some sanity with respect to time. For example, Queensland, also in Australia sensibly spurns Daylight Saving time and has a straightforward relationship to GMT year-around. If people there try to meet with people according to clocks set in areas which follow Daylight Saving time then through no fault of their own they have to cater for times dancing back and forth an hour twice a year at mystically derived times.
Finally, this breaks down into utter chaos when you need to coordinate many meetings which run to many different clocks, some of which are on Daylight Saving time for the Northern Hemisphere, some of which are on Daylight Saving time for the Southern Hemisphere, and some that use sane time.
The most absurd thing of all is that Daylight Saving time doesn't actually save anything. Some people haven't the presence of mind to get up early and make use of the extra daylight in the morning to get things done before their daytime schedule begins. All the people who are quite happy to make sensible use of their time are penalised because the hopeless ones are, by royal decree, forced to get up early; Daylight Saving starts their schedule an hour sooner. This is plain stupid as any person who lives their life at all closely to the land can tell you (pity the poor farmers).
But now that we have entered the era of the global village coordinating all these places with shifting times makes for a great deal of unnecessary confusion.
(Whew! You can tell this is one of my pet hates can't you. :)