Yup, the actual time zones still exist. Just because we all switch to UTC doesn't make the differences in time disappear. It's now just hidden. Meanwhile, days

Yup, the actual time zones still exist. Just because we all switch to UTC doesn't make the differences in time disappear. It's now just hidden. Meanwhile, days just got really confusing! All sorts of phrases would suddenly become ambiguous. “Dinner at my house on Wednesday?”, “Want to see a movie on Saturday?”. Both of those phrases would become confusing when dinnertime on a Wednesday could be 01:00 UTC or 23:00 UTC. Same with the movie: did you mean as Saturday is just ending, or just starting?