The XML way is very good for XMLs purpose, which is enabling generic tooling that doesn't need to understand the semantics of the particular application language, which is great for building a foundation for tooling to support thousands of application languages most of which will have very few users so it is very good if much of the tooling cost is smeared across lots of other languages.

HTML is important enough that it warrants direct investment in tooling and doesn’t need the XML approach.