The C++ library and Chapel were solving the same problem, but Chapel (in the author's framing) did it better. Javascript and Typescript solve the same problem, but Typescript (in the view of people who care about type systems) does it better.
Nushell is not trying to solve the same problems as a shell:
> Nushell is really an interactive, data-focused scripting language with shell capabilities.
Great, but that's not the problem I give a damn about. If I want an interactive, data-focused scripting language I will use Python. And against Python, Nushell is not nearly as attractive.
Nushell is trying to blend two domains, shells and programming languages, which I see distinct advantages in keeping seperate. I do not want the world to be built on the back of shell scripts, regardless of how good you make the type system. I do not want to ask more of shell scripts and view that as a negative.