No it doesn't. It demonstrates that Minecraft's solution is heavy. Minecraft is a cellular automaton. That's why its slow. It would be a mistake to believe that minecraft demonstrates the effectiveness of voxel technology.
Minecraft clearly demonstrates the comparitive heaviness of using voxel arrays to represent a world in contrast to a polygon mesh. This point is trivial, and is not unique to Minecraft.
Additionally I'm finding a large number of comments that begin with "No it doesn't", then either stating an identical argument to the parent, or not attempting to refute the parent comment at all. If you're doing this for "points" then shame on you.