There are lots of reason for why text is preferable though. I did some work on an drag-and-drop sort of a programming language for a ETL pipeline a while back.

There are lots of reason for why text is preferable though. I did some work on an drag-and-drop sort of a programming language for a ETL pipeline a while back. The absence of unit test cases makes it very hard to deploy changes without being sure you are not introducing breaking changes. There are other things as well. People tend to make big flow in one canvas. Which makes it very hard to understand. There are few more things, like wherever a GUI component relevant to a case was missing, the tool provided a way to add a javascript snippet, eventually on some canvases all you see is JS components talking to each other. At that point you are better off writing plain JS code.