Not all parts of a system can be independent of changes to how time is interpreted or displayed. E.g. in a calendar: what happens to the time of a recurring mee

Not all parts of a system can be independent of changes to how time is interpreted or displayed. E.g. in a calendar: what happens to the time of a recurring meeting after a DST transition? What if participants are in different time zones with different DST rules? But as long as you only need to track time for dealing with time intervals in an abstract fashion, you can get away with a nice continuous and monotonous scalar representation of timestamps.