"Word’s intellectual model is effectively timeless: you paint the text with its attributes. WordPerfect’s is active and progressive: you change a setting, continue typing, and then change some other setting"

Umm... those are the same basic model.

WordPerfect's model is simply more primitive markup. The only difference is, unlike a structural document editor, the markup isn't containers, they're just control directives. In essence you "paint" a region of text with a directive by changing a setting, then changing it back.

Word fails for a very simple reason: they've shoehorned structural editing functions, with styles and sections and so forth, into an editor that traditionally worked like WordPerfect. The result is a complex mishmash of ad hoc and structural document markup, and you end up with confusing rules in order to reconcile the models.

Personally, I prefer LyX: powered by LaTeX, it's purely structural, while providing a rich editing environment with a visual approximation of the output, where the final document is typeset to the desired format. The result is simple and freeing: I concern myself with the content and the structure, let LyX manage the underlying markup, and let the typesetter decide how to lay it out.