And I'll get back to my original point.

When Debian demoted bash and migrated to the Almquist shell, there was great anguish from Ubuntu users of all tiers (Adobe was notable, IIRC).

That anguish was due to a decade that predated POSIX.2.

That was a substantial hindrance.

I absolutely remember Debian switching to Almquist shell, but that was about more than just POSIX compliance. IIRC a big deal at the time was that the cost of starting and using GNU bash all over the place was actually a measurable performance impact, and switching to dash improved on this. Also, bashisms became pervasive in scripts with /bin/sh hashbangs, which is definitely wrong no matter how you feel about POSIX.

And anyway, this tangent doesn't feel terribly connected to this discussion thread since macOS never had this issue in the first place and this particular discussion thread was never really about UNIX shells...