In a recent interview on html5doctor by Bruce Lawson of new Doctor Steve Faulkner, someone asked why HTML5 document outline wasn’t being implemented as expected.
Answer:
http://html5doctor.com/interview-steve-faulkner-html5-editor-new-doctor/
So the outline is at risk and developers should be wary of using it. Also ran across this tweet from Steve:
He mentions JAWS can/will announce each region and if you’ve got hundreds of them they get tedious 
So it there any point in using new elements like <section> at all? I’ve still never used any of these structural elements. Just don’t see the point. (O, portability? Puh …)
Sure. They are meant to have proper semantics where div and span still don’t (and shouldn’t). Roles are also natively associated with them.
It means now
be conservative with sections and articles. Use them as large wrappers rather than wrapping every possible little sub-something in them-- consider using divs for that.
don’t choose outline-sectioning elements based on an expectation of making a document outline, since it’s at-risk.
If you have a large chunk of content that really is an article, or a large page section, go ahead and use them if you want.