It is still pretty relevant, as the .bat file contents can't prevent improper arguments from executing arbitrary code, whereas a #!/bin/sh file invoked with arbitrary arguments will not do any code execution other than what the file itself asks for. And, even still, the #! form will still pass the arguments as separate elements, i.e. a file containing "#!python3" invoked via an execve argv of ["the-file", "arg1 \"foo ^%`'\\", "arg2"] will result in a total invocation of ["python3", "the-file", "arg1 \"foo ^%`'\\", "arg2"] (JSON-formatted here for clarity reasons, there's no backslash-escaping happening anywhere in reality).