They're giant single-piece layered composite structures. Crafting the blade onsite means you have to build then unbuild a giant plant next to each wind farm.
> Lundstrom says 3D-printed blades will never happen, since it would require a large, sophisticated manufacturing facility to be built at every wind farm.
I assumed this was already being done for the massive offshore models. Setup some kind of minimal plant on shore so you minimize transportation to the boats.