I don't accepts axiom 1 as valid.

  1. The mapping between DOM content and Visible content should be well-behaved.

I don't see why the same edit, applied to two documents with visually identical renderings, should again produce two identical renders.

As a simple example, take document (a) consisting of the words 'an axiom' styled white on a white background, and document (b) an empty document with default styling of black text on a white background. Both would appear blank.

Now apply an edit, say inserting the text 'a fallacy' into both documents. After the edit, document (a) can be expected to remain blank while document (b) can be expected to show 'a fallacy'.