As someone that also has a background in digital circuits tooling, I think that the problem is the spaghetti codding that usually leads to monoliths.

While on text based languages, lack of modularity is kind of hidden and only jumps at you when you try to actually change anything, on visual languages it jumps right at you when you open a project.

Ideally, anything that requires panning or zooming, should be packed into their own little reusable building block, instead many try to package as much as they can into a single screen.