> you really need to have a specific reason to choose something outside of bash/zsh/fish
The reason in question is that not that long ago, people said "you really need to have a specific reason to choose something outside of bash", and people choosing to go off the beaten path lead to zsh and fish becoming powerful and way more popular/well-supported than they were before.
"Popularity" probably has more to do with Apple moving to Zsh than anything else. Zsh has been more powerful than Bash for literally the entirety of the existence of both. It surely was back in like 1993 when I first looked at them. The "emacs of shells" might not be the worst summary.
Fish is a more recent addition, but I hate its `for loop` syntax, seemingly copied from BSD C Shell, which this Ion shell seems to have copied (or maybe Matlab or Julia?). Baffles me to impose a need for `end` statements in 2025. In Zsh, for a simple single command, I need only say `for i in *;echo $i` - about as concise as Python or Nim. In the minimalism aesthetic, Plan 9 rc was nicer even before POSIX even really got going (technically POSIX was the year before Plan 9 rc) for quoting rules if nothing else.
I think it's more insightful to introspect the origins of the "choosing something outside bash" rule you mentioned. I think that comes from generic "stick to POSIX" minimalism where Bash was just the most commonly installed attempt to do only (mostly) POSIX shell.. maybe with a dash of "crotchety sysadmins not wanting to install new shells for users".
Speaking of, the dash shell has been the default on Debian for a long while. So, I think really the rule has always been something "outside POSIX shell", and its origins are simply portability and all those bashisms are still kind of a PITA.
> "Popularity" probably has more to do with Apple moving to Zsh than anything else. Zsh has been more powerful than Bash for literally the entirety of the existence of both. It surely was back in like 1993 when I first looked at them. The "emacs of shells" might not be the worst summary.
It's my impression that Apple switched to zsh because it's permissively licensed, so they could replace the now-ancient last version of bash to use GPLv2 (instead of v3). Obviously it helped that they could replace it with something even more feature-rich, but I expect they would have taken the exact same functionality under a more permissive license.
The reason in question is that not that long ago, people said "you really need to have a specific reason to choose something outside of bash", and people choosing to go off the beaten path lead to zsh and fish becoming powerful and way more popular/well-supported than they were before.