Your example is valid and replies are ill-informed. There is a difference between a "date" and "time interval". Timestamps are good for storing intervals, but if you need to plan something on a _date_, you need to store the date. This means you care not about specific number of seconds having passed since now, but about what calendar (and the clock) is saying when the event has to happen.

Example: nobody cares if a concert planned on November 19, 2024 at 19:00 in Honolulu starts in 12345600 seconds or 12349200 seconds since now. But everyone cares that everone's calendars and watches are in sync by that time and show specifically that date and that time, regardless of how many times people switched DST or timezones in the years in-between.