Simplest possible smooth contouring algorithm

Very interesting, and I like the interactive graphics. I've been looking at this problem recently with an eye towards what it looks like to translate scene descriptions from an SDF (signed distance function) representation of a CSG (constructive solid geometry) scene to a triangular-mesh representation. I've looked at marching cubes, which has another page on this site that is linked from this page, but it seems kind of inelegant.

The obvious problem with this method is that it relies in the underlying object being smooth, and many CSG designs have cusps and other non-smooth artifacts that are very hard to derive from an abstract representation because the SDF is not well-behaved around those regions.

It's pretty easy to create weird loops in the contour by placing two dots with about ~0.5r of distance between the edges.

What makes this the simplest possible algorithm?

I really have a problem with this article, not because of the algorithm, but because of the presentation:

    for(x...)
    for(y...)
    for(z...) {
      ...
    }

I believe that code should at least attempt to be literate, and this just makes me shake my head in frustration.