On IBM i (originally known as OS/400), you can press a function key and automatically get a fill-in-form for any command.

This is because command line syntax is defined, not in your program's code (getopt calls etc), but using declarations in what you might consider to be a separate command definition file (technically called a "*CMD object"). The OS does command line parsing and validation, marshals the result into a memory block, and passes that to your program rather than the raw command line. And the OS uses the same command syntax declarations to generate the (text mode) fill-in form for display.

Other systems which use the idea of command line syntax declarations, with the shell doing option parsing based on those declarations instead of each program doing them itself, include OpenVMS DCL and PowerShell. (PowerShell actually copied this idea from OpenVMS DCL and IBM OS/400.)

I think the big reason why this is less common in Unix-like systems, is the design decision to give each command responsibility for parsing arguments/options, rather than doing it in the shell. This makes the whole approach of automatically generating fill-in forms at the worst impossible, at the best unreliable. You can try parsing --help output or man pages, but that method isn't always going to work, centralising option parsing in the shell does. It is likely rather too late for Unix-like systems to change their approach.