Sure, but code has a level of complexity that boxes and lines abstract away. If you want to describe a certain level of complexity, you'll need code or something that achieves a similar level of capability. If you don't need that high level of complexity, often because you're abstracting complexity away, it's hard to find an alternative that isn't better than boxes and lines. If there's a better alternative, nobody's found it yet. Boxes and lines appear to be a final state to which all roads lead.