As I see it, that the whole point in this case. Alexander wants to teach children how to program in text mode, but can't see the bridge from Scratch to text mode. With textboxes, the child can write small functions to start with. As they learn, they may well start making the blocks of code more complex. Eventually they might end up with a single block with everything in it, as you describe. At that point they ditch the Scratch "wrapper" and start using a typical text mode tool chain. Mission accomplished.

One of my children did something like this. In the days when Scratch was written in Squeak, he discovered that shift-clicking the 'r' in the Scratch logo dropped him into the underlying Squeak environment. He then started modifying and writing Scratch blocks and was eventually comfortable with text mode programming.