The height is uniform iff you measure height from the perspective of the rotation of the bar rather than the perspective of the chart. Confusing wording, but th

The height is uniform iff you measure height from the perspective of the rotation of the bar rather than the perspective of the chart. Confusing wording, but they meant the displayed vertical size in the chart instead of the length of the bar. I think a traditional vertical stacked bar chart would have been far better.