People have suggested using the control characters for CSV structured files. The problem is that they are impossible to edit.

Control characters are invisible, using them means changing text editors to display them. They are also, outside the usual ones, hard to type. ASCII ones have Ctrl combos, but editors used those for other things.

Also, what is the difference between using some new character to start block and "{" or "\n"? Why have new thing to indicate new level when have space and tab?