I've just been prompted to think about this by reading this dated question: Jackson based IDE for programming
But the issue had already been on my mind recently.
Why do attempts at "visual designers", visual programming, and diagrammatic representations of programs persist?
I'm not talking about ad-hoc diagrams for human consumption, either to explain concepts or to supplement something that is found to be difficult to express in a particular programming language.
I mean visuals and diagrams that are systematic in some way, and which attempt to cover the same ground as written programming languages. A systematic approach which basically starts from the idea that everything is difficult to express in a written programming language, and therefore a visual method should be used instead.
It seems to me there have been a variety of schemes over many decades now, and all eventually seem to fall by the wayside.
Untrained novices seem not to be automatically drawn to such diagrammatic representations, and experts tend to shun them either as simplistic or as obscuring.
But they are often advocated for as something that somehow makes things easier - either for novices or for experienced practitioners.
What are the views and experiences of educators on the effectiveness of "visual programming languages", either as teaching aids or as something that really helps productivity?