I know 2015 wasn’t that long ago (I’m pretty old too :) ) but it wasn’t that long ago when language support for Unicode was patchy (Go is only 12 years old and it was a big thing that supporting Unicode out of the box). Even as late as 2015 some popular desktop applications either didn’t support Unicode or didn’t default to it. MySQL only supported utf8mb4 in 2010 and it took a few years for that version to become wide spread. Plenty of servers I managed back then didn’t even have Unicode locales installed.
To be clear, even in 2015 _I_ personally would have recommended Unicode (like yourself) because it was clear that it was, and is, the future. But I can forgive some people for being cautious about it even as late as 2015 if universal comparability was their concern.
My point is, if you’re only targeting English speakers _and_ you’re primary concern is portability then ASCII isn’t wasn’t unreasonable recommendation.
To be clear, even in 2015 _I_ personally would have recommended Unicode (like yourself) because it was clear that it was, and is, the future. But I can forgive some people for being cautious about it even as late as 2015 if universal comparability was their concern.
My point is, if you’re only targeting English speakers _and_ you’re primary concern is portability then ASCII isn’t wasn’t unreasonable recommendation.