I totally agree but Id also like to point out that visual debugging on itself is impractical (although cool and easy to pick up). It has its place in education though.
I'm not entirely sure what you mean. But I think a visual data wrangling tool (like my Easy Data Transform) is easier to debug than it's code based equivalent (like Python + Pandas) because you can click on each node in turn and see exactly what is happening, step by step.