So there is no technical limitation of HTML itself compared to XML (doc format)? That HTML would be a just as good replacement for XML (.doc format) if someone tried to make a word processor for it?
The HTML document alternative was a massive technical hack. It was flawed mandate from executives in order to maintain relevance in web-based world. Embedded XML and custom styles were used to implemented the format. Also, the IE team worked closely with Office to support richer text formatting. HTML was not enough. Even then, the format still could not support all the features in the product--features like versioning, simultaneous editing, ole embedding, programmability, etc.