This reminds me of an old joke about binary XML:

   <byte> 
   <bit>1</bit> <bit>1</bit> <bit>0</bit> <bit>1</bit>
   <bit>0</bit> <bit>1</bit> <bit>1</bit> <bit>0</bit>
   </byte>

>It's easy to make a concise representation of DOM trees as JSON: http://m1el.github.io/jsonht.htm

It is not concise. Here is an example of a single div tag overhead:

   ["div",{"class":"some classes"}, ... ]

   <div class="some classes"> ... </div>

Also, it does not represent DOM trees as JSON. It represents DOM trees as S-Exressions encoded via JSON. The s-expression above can be written directly as:

(div (class= "some classes") ... )

So why does it need to be wrapped in a format that's verbose, underspecified, doesn't have comments, doesn't have namespaces and doesn't have any notion of metadata?