That's like saying it's impossible to design a motherboard because you can't show all the bypass capacitors on the top level schematic. Hierarchical design and layers of abstraction are vital in both hardware and software.

True; but visual programming means you need more 2D space (screen) to see the same amount of logic. Maybe with bigger screens it could work better?

Which is; > "The problem with visual programming is that you can’t have more than 50 visual primitives on the screen at the same time."