The author makes a case that every 3D print manufacture has known since the day they started. Each "squirt" of print media is a volumetric dot. A Voxel.
The problem is that each brand printer has a different sized "dot". So the Voxels from one format might not directly correspond to your object. Sure some printers could print at a lower resolution [larger dot / voxel], but rendering a pattern from a smaller voxel to a larger is VERY difficult. Errors result in pieces that don't connect, or detail being removed.
Polygons work like the "How many tennis balls on the bus" and create a container for the media, but also allow for non spherical output. You can build a column or an arch from a steady stream of media. You can't do this with voxels.
Voxels would work better if we were in Zero Gs as well because Printers can't actually make round dots, they are always deformed by gravity and contact.