Powershell idea isn't new, it is how REPL worked across all Xerox PARC workstations.
While Windows isn't a whole language OS like those, .NET and COM gets pretty close to it, and that is what PowerShell knows about, instead of raw text.
This is what is missing across most traditional UNIX shells, integrate raw text, UNIX IPC (and newer ones like D-BUS/gRPC), shared libraries, structured data, into a single REPL experience.
While Windows isn't a whole language OS like those, .NET and COM gets pretty close to it, and that is what PowerShell knows about, instead of raw text.
This is what is missing across most traditional UNIX shells, integrate raw text, UNIX IPC (and newer ones like D-BUS/gRPC), shared libraries, structured data, into a single REPL experience.