I don’t think a general purpose scripting language is simpler than this variables feature. As you rightly point out, sh already exists for more complex use-case

I don’t think a general purpose scripting language is simpler than this variables feature. As you rightly point out, sh already exists for more complex use-cases, and really complicated stuff can be handled by a helper program. For me, the big value-add is the filter functions - for example, proper JSON escaping or URL encoding is hard to do with pure sh, usually needing some external tool; now that it’s built into curl, it will simplify scripts and reduce the list of dependencies.