This doesn't help in any way, shape or form. You have pissed off billions of people who have had to re-learn custom times for things, you have caused the weekday to flip in the middle of the day for billions of people, and you STILL haven't solved the problem of "Can I call Uncle Steve in Melbourne, or is he sleeping right now?"
There is no way to solve that problem of Uncle Steve (imo). But there is no difference in saying Steve is +8 hours so our noon is his 20:00 and or saying we should only call Steve between 03:00 and 20:00 UTC. It is an offset either way. It is only jarring to think that way now because it is the one way people have.
There is also the problem of someone driving across the US and suddenly they pass an invisible line and now it is one hour in the past or the future. The day changing while you work already happens for everyone working 3rd shift.
Billions of dollars in waste and confusion happen today because of forgetting about timezones. One study suggests that international trade is decreased by 5% per timezone between countries.
Also, please don't post snarky comments in the first place. This is in the site guidelines as well: https://news.ycombinator.com/newsguidelines.html.
Why ruin a good post with that last, grossly inappropriate line?
I think there is a simple plan that isn't disruptive. Simply require that all times be listed in both formats. For example, 9:00 am EDT (13:00 UTC) for all printed times on all signs, etc. moving forward from some day in the future. Eventually, we can drop the first as people adjust. (This is already how we re-number or rename highway exits)