In my view Debian boiled an ocean for no discernable gain and caused a lot of trouble for everyone in the process. Fedora is using bash and I hope we continue rejecting the mistake Debian made.
If your shebang is `/bin/sh`, then it's nice to have a strictly POSIX-compliant shell.
Arrays are still available in POSIX mode, even though they do not comply.
The dash shell has been reported to be four times faster than bash.
That definitely impacts boot time. POSIX compliance is not the only benefit.
The Unix world is better off if there is the option of using another shell that isn’t bug for bug compatible with bash.
This behavior is what leads to systems that have to emulate ancient bloated interfaces because they need to support applications that use apis that are defined as ‘how that program does it’. That’s bad. We should avoid it. Avoiding it is a benefit.
Busybox actually takes dash, and then sprinkles a few bash/korn features back onto it (notibly, not arrays).
If you want a lot of people to use your scripts, getting them working in dash can help a great deal.
The POSIX mode in bash exists because bash itself predates POSIX by nearly a decade.
It's like saying you'll never use any Linux feature except those strictly defined by POSIX.1. Why would you do that?
The fundamental reality is that GPL does not run on iOS or Android (in userland). If you want to run scripts on those platforms (and they are ENORMOUS), then you cannot use bashisms.
Full stop.