When I propose wacky, implausible ideas to friends like "a single world-wide time zone" or "replacing all writing with the international phonetic alphabet", the idea is to reduce things that make the technical debt for supporting the whole world enormous.
As it is, English programmers are frankly, most likely to make things that only work for English speakers. And then the technical debt of supporting Latin alphabets and US time zones and all the like multiply together. We should be thankful as much of the world adopted UTF8 and UTC as early as it did, but I don't envy anyone who has to work with systems that don't have good support for internationalization. Those people are in a terrible position, and with legacy systems, they might have to implement a terribly complex set of rules that are taken for granted by most people, and sometimes not even explicitly written down anywhere outside obscure papers on the topics.
Someone mentioned the current year in the Nepali calendar is 2071. So now you know, if you want to appropriately support customers in Nepal, you might want to support their calendar. But I don't know enough about Nepal to say whether or not anyone does. The Wikipedia page List of calendars is, frankly, a bit terrifying[1].
The fundamental problems of these fun cultural artifacts is the technical debt for old systems and the barrier to entry for new systems.