The main purpose of the 3D is to communicate the extreme differences in scale of value, which chloropleth alone doesn’t always get across as it flattens the magnitude disparity. Keeping true north to avoid confusion is a good point.

+1. Also, I had to go look at their interactive viewer because that color scheme choice (dark purple = low, light green = high) seemed 100% bonkers. It's the legit "plasma" scheme, but based on my limited experience with colorbrewer schemes, I was confused.

Yeah, I agree. And if the surface is complex the Z features tend to obscure the complexity. I make maps like these for the cities of Berkeley and Oakland, but I use a color scale. And I usually aggregate at a larger granule than parcels. For e.g. https://observablehq.com/@jwb/2024-25-berkeley-property-tax-...