You're right, this used to be "the way" to make text that didn't scale on zoom, back when IE6 was king. But now that Firefox, Safari, and all the cool kids have pretty much standardized full-page-zoom instead of page-layout-zoom, I guess the IE team is being stubborn about moving to the new way of doing things.

On a related note, I still haven't seen any full-viewport HTML5 apps that don't break terribly on zoom in some/all browsers. It really is a terribly tricky behavior to understand, and probably the least consistently implemented.