But it's a core part of the concept, the whole idea behind a markup language. Basically the whole point of HTML, and even of SGML before it, is that you are add

But it's a core part of the concept, the whole idea behind a markup language. Basically the whole point of HTML, and even of SGML before it, is that you are adding annotations in-line in a text, not representing a text as a tree-like data structure, at least for much of it.