i disagree that this is better because the OP is about why you would choose a given viz and what it actually expresses usefully, where this example is just pictures people can fit their data to for slides.
direction matters. most sankey diagrams could be pie charts (eg the birthday sankey) and dumb usages discredit useful viz techniques.
nested boxes are usually trees, and mixed nested boxes with lines without symmetry are almost always lazy reasoning or bullshit. start with symmetry and intent and it will be apparent.
