Nice run down. But in this context it seems to boil down to
> I have the feeling that trying to address these points by bolting features or DSLs onto a general-purpose programming language doesn't work. At least, I have yet to see a convincing implementation of it.
… and what is worth doing, a new shell or new features in an old language, which isn’t addressed by that post AFAICT.
A short answer would be that dozens of projects like this already exist and have existed for decades (scsh was mentioned in this thread), and they aren't widely used as shell replacements:
> I have the feeling that trying to address these points by bolting features or DSLs onto a general-purpose programming language doesn't work. At least, I have yet to see a convincing implementation of it.
… and what is worth doing, a new shell or new features in an old language, which isn’t addressed by that post AFAICT.