[arp242]

> It's not really "Who knows". We actually do know.

I'm not so sure about that to be honest. A few years ago (around 2020 or 2021 IIRC) autotools switched from the old deprecated backquotes to $(..) to run programs in shell, and people complained that it no longer worked with their SunOS shell or some such. I've also seen some Vim bug reports about stuff breaking on obscure old systems. In short, I think you may be underestimating the "long tail" of weird/old systems.

Personally, I'd say it's perfectly reasonable to just say "sorry, we're not supporting that any more, you can keep using the existing version" because the number of people doing this seems quite small. But they do seem to exist.