I can tell you from bitter experience that if you have an event where a person has to arrive at a place at a time and you store that as UTC instead of wall clock, you will have a problem at some point
The future is defined by intent which is imprecise (will Oregon drop daylight savings time or not — who knows?). I don’t know how many seconds it is until my next birthday, but I know exactly how many have passed since I was born.
Maybe a better argument is, “when you’re setting a phone alarm, you don’t tell it a timezone.” Maybe the distinction is whether the timezone is established at write time or read time.
Which coincidentally and ironically makes phone alarms surprisingly difficult to implement in a way that does not break in the face of DST shifts, timezone changes etc., as Apple has learned the hard way a couple of times.
Past/future does matter, as generally speaking it's possible to accurately convert between local time and UTC for times in the past, but not in the future.
There's a few exceptions where governments have retroactively changed timezones or DST rules, but at that point you've lost anyway.