So, it sounds like you're actually arguing that the numbers are just a construct and that we should all just use UTC and set appropriate work hours to the times that most correlate to the solar day in our region rather than adjust the clock approximately 1 hour per 15 degrees around the equator and have an International Date Line.
I think this would make way more sense, when they say the Olympic Opening Ceremony start at 18:00, its 18:00 for everyone around the world. No one as to work out which TZ Italy is in or scheduling meetings with Tech Support in far flung locales does not require knowing IST is how far ahead or behind.