That is fine as long as the input / output is always in UTC... but at the end of the day you often want to communicate that timepoint to a human user (e.g. an appointment time, the time at which some event happened, etc.), which is when our stupid monkey brains expect the ascii string you are showing us to actually make sense in our specific locale (including all of the warts each of those particular timezones have, including leap second, DST, etc.)