Advantages:

• We could use it in WebWorker, Server side, or with native renderers.
• Proper camel casing. (We can get rid of inner-html vs innerHTML) Use camelCase instead of dash-case in HTML #4923
• Errors have proper line numbers.
• We can rely on attribute order (not sure if it would be relevant)
• We could support self closing tags <name /> for custom elements
• No need to ship parser when doing offline compilation.

/cc: @pkozlowski-opensource, @gdi2290, @tbosch