Earlier quoted context omitted.
Nobody draws voxels, graphics cards aren't good at them. I don't know about these engines in particular, but in minecraft everything is converted to polygon meshes.
Nobody these days, but one of my all-time favorite games is Outcast[1], which used voxels for the terrain and polygons for smaller details. All it needed was a good CPU. [1] https://en.wikipedia.org/wiki/Outcast_%28video_game%29
Also there was https://en.wikipedia.org/wiki/Comanche_series even before Outcast. I don't think it used polygons. It was launched years before 3D graphics cards, too..