Or think about traveling. At home, you set your alarm for 6 AM. You really like waking up at this time even when you travel. You want time to hit the gym, and eat a nice breakfast. Now, in a world without timezones, you travel to SF. When your flight lands at 5 PM, what phase in the day is it? Local “morning”? Local “late evening”? Are you going to have a hard time catching a taxi? What time do people eat breakfast there? What time should you set your alarm for?
So you need a translation layer from your location to another location to know what phase in the day it is for people in the other location. Is it their “morning”? Their “afternoon”? Their “business hours”? When do they sleep?
That translation layer exists. That’s timezones.
Abolishing timezones doesn’t make coordination problems easier. In fact, it makes them harder. The time on the clock might be the same around the world, but when people do things (wake up, eat breakfast, conduct business, grab a cocktail) would vary around the world. (Yes, it’s true there’s regional variance to these things today, but for the most part you can rely on morning having a rough relationship with when people wake up and sunrise, for example.)