Article, aside and address elements can be used in many different ways on web pages.   By allowing these elements to have a role="region" they can be used to identify sub-sections within top level landmarks like role=main.

For example:

<section role="main">
  <h1>My New Paper</h1>

  <article role="region" aria-labelledby="art1">
    <h2 id="art1">My First Article</h2>
    <p>para 1...</p>
    <p>para 2...</p>
  </article>

  <article role="region" aria-labelledby="art2">
    <h2 id="art2">My Second Article</h2>
    <p>para 3...</p>
    <p>para 4...</p>
  </article>

  <article role="region" aria-labelledby="art3">
    <h2 id="art3">My Third Article</h2>
    <p>para 5...</p>
    <p>para 6...</p>
  </article>

  <aside role="region" aria-label="Today's weather">
    <div> ... weather information ...</div>
  <aside>

</section>

<footer role="complementary">

  <address role="region" aria-label="My News Paper Contact information">

  </address>


</footer>