I think you should take into account that plants can differ enormously. Small plants that don't grow in tight grids get some fancy 14x multiplier but once you actually try to grow a space efficient plant like wheat it just doesn't work out. The crop is already maximizing exposure to the sun to an incredible degree. Vertical farming can't increase this "efficiency" other than by adding more layers which will always involve uneconomical artificial lighting.
Growing easy plants... is easy. Not every plant is easy to grow in a vertical farm.
Personally, I like light pipe tecnology. But I still don't get it. If wheat is already maxised for land/light and cannot be improved then what could be the theoretical advantage to indoor growing of wheat partially under light pipes?
Area/energy-wise the best it can ever grow indoors is surely no better than on the roof.
Growing easy plants... is easy. Not every plant is easy to grow in a vertical farm.