It many not be obvious at a first glance, but a lot of what you see here is the result of copying and pasting.
It is true that non-voxel edition systems also have copying, but I believe this is a very different mechanic. A voxel clipboard is a new thing.
When you paste objects in a mesh based system (like Maya, or a traditional game engine editor), you are cloning objects or creating instances of them. This is very cool and allows you to do many invaluable tricks, however, every time you paste a new object goes into the scene. If you paste overlapping an existing object they do not merge into one. In some sense, pasting in mesh systems does not help you build a larger thing. You build an assembly of things.
In mesh based editors you get a sense that every paste counts. The scene complexity grows every time you press that Ctrl+V. Yes you could stack some boolean modifiers and have any new pasted meshes in them, but this is getting complex now. My interest is systems anyone at home can figure out.
Copy-Paste with voxels feels organic. It is more like the clipboard in a word processor. You get things you like and combine them in a new form. Then you copy the new form and use it as an element of something else. All this time you are working on only one thing, it remains simple in your mind. You are not leaving a long trail of objects behind you.
One thing is certain, we are taking the clipboard very seriously now. Here is a video showing some new cool tricks we are able to do:
There are still aliasing issues, just like with our line tool, so some configurations may not paste back into pristine conditions. I think this is alright as long as you remain aware of what the limits are. And of course, our plan is to continue to bring down these limits.