In many contexts that doesn't really matter. Sure, from a programmer point of view that's a problem because there are potential cases with incorrect or ambiguou

In many contexts that doesn't really matter. Sure, from a programmer point of view that's a problem because there are potential cases with incorrect or ambiguous behaviour, but being able to sort files by date could be useful in cases where that level of correctness and granularity don't matter. You might just have a bunch of files from around the year that you just know won't ever be that close together in time, and which you perhaps also only ever touch manually, not programmatically. I once chaired a smallish organization, and I used to name the minutes of meeting files with ISO 8601 style. If you have a dozen or so files from throughout the year, having them reliably sorted can make them easier to find, but there's never a problem with time zones or basically anything with granularity greater than a day. Usually, if you've got a situation where you need to worry about time zones or DST, identifying things with year-month-day style timestamps treated as strings would be too low-tech a solution anyway. (FWIW, the practice of using ISO 8601 didn't last, presumably because non-technical people didn't find them that nice for one reason or another.)