If you think that, you don't understand the nature of what is being done with HTML nowadays. It's not about declarative markup, it's about efficient updating of a UI whose shape is completely decoupled from the shape of the state it is representing.
Meanwhile QML provides you with the same kind of programming paradigm except that you do not have a DOM, you have the QtQuick Scene Graph which calculates how to render your new state in the most efficient way; and, worth mentioning, in a much more efficient way than a standard browser stack would be able to under regular circumstances.