Sometimes you need your timestamps to be in a named timezone. If I have a meeting at 9am local time next month, I probably want it to still be at 9am even if the government suddenly decided to cancel daylight time.
At some point you need real time aware libraries and whatever language you use they've been through several iterations of them (Javascript Date, moment, dayjs, ...) because they got it wrong the first time and probably the second time to.
With ISO 8601 it is easy to get the yyyy, yyyy-mm, hh and other things you might work with primitive tools (awk). Getting the day of the week or the time involved is not hard which gets you to the chronological rosetta stone
https://en.wikipedia.org/wiki/Julian_day
which is a multiplier and and offset away from Unixtime except for all those leap seconds and whatnot. With Unix timestamps comparison is easy and differences are easy and even knowing it is Thorsday is easy; they don't sort as strings but GNU sort has a -n option, only trouble is it is a bunch of twisty little numbers that look alike.