The entire convention of time zones should be abandoned.

Disagree. If we all worked to GMT a lot of us would be sleeping in daylight. Not good for peoples' demeanour. And there are plenty of studies that speak of shiftworkers average life expectancy being lower and depress more prevalent.

Or if we all used GMT but worked roughly to daylight hours, there would be a clash of understanding about, say, what hour breakfast was. (23:00 for some!).

Life is complicated - innit?