My point is that you can build very high off the ground with wood/iron and still get blue (grounded) connections with standard wood or core. For instance roof pieces are made from regular wood. I once made a three floor castle (counting the roof) (4 if you count the towers) out of only stone and wood/iron. It was massive and had no center supports. A stone floor will work as a roof for the purpose of the “shelter” effect.

Would not be nearly possible without wood/iron

Also wood/iron allows for something like 15 or 16 connections before you no longer build , pretty sure stone will not get you that far. And stone columns cannot be placed horizontally