And now no one can forget to close the file, plus it’s shorter as well. There is no way to do this in a non Lisp language.

C# has the IDisposable + using construct for exactly this purpose. If you're not happy with that you can write your own using a lambda, just like his example...

  using (open file here)
  {
    // Do work here
  }

  WithNetFile(f => do work here);

Lisp is neat, this is not a great argument though.