One of the great things about trees is that they provide natural context for
content. And when people edit content inside a tree, they are aware of that
context. That is the reason why an author will know that a
element inside a
circle element will be the title for that
circle, and not for the entire document.
Failing to use context in naming elements or attributes entails a loss in
language fluidity. Some vocabularies that have strong roots in SGML
have an excuse for this approach since DTDs named elements globally. This is
visible in DocBook for instance: it feels daft to call every item in a list a
listitem since it appears as the child of one of DocBook's many
list elements, but that was necessary in those days from before broadcast radio
and widespread tap water.
More recent languages have no such excuse. For instance SVG has a long list
of elements beginning with "fe":
feTurbulence... That "fe" is meant to signify "filter effect". But the
fact is that these elements can only appear as children of the
element — they are always going to be in a filter effect defining context. The
prefix just makes them more clumsy, as if all SVG elements began with "svg".