I think the big application of visual programming is in domains where the concrete "unit operations" map neatly to programming functions. For example, things like this:

https://www.aspentech.com/uploadedImages/Community/Blogs/Eng...

That chemical process simulator lets engineers who are bad "text programmers" make complex chemical process simulations by giving them a library of functions that correspond neatly with the set of tools the engineer is used to thinking about. Indeed, other engineers can discern the intent of a flowsheet made in this tool faster than they could if they were looking at the text-code.