Q:

HTML5 headings: is the HTML validator out of date?

W3C says in their HTML5 section recommendation, that 
<body>
    <h1>Let's call it a draw(ing surface)</h1>
    <h2>Diving in</h2>
    <h2>Simple shapes</h2>
    <h2>Canvas coordinates</h2>
    <h3>Canvas coordinates diagram</h3>
    <h2>Paths</h2>
</body>

and
<body>
    <h1>Let's call it a draw(ing surface)</h1>
    <section>
        <h1>Diving in</h1>
    </section>
    <section>
        <h1>Simple shapes</h1>
    </section>
    <section>
        <h1>Canvas coordinates</h1>
        <section>
            <h1>Canvas coordinates diagram</h1>
        </section>
    </section>
    <section>
        <h1>Paths</h1>
    </section>
</body>

are "semantically equivalent".
If so, why is the W3C HTML validator warning about the latter example? 
It says about the second example:

Warning: Consider using the h1 element as a top-level heading only
  (all h1 elements are treated as top-level headings by many screen
  readers and other tools).

Is the validator wrong?

A:

No.
The Validator is warning about real world behaviour by software that is in the wild. Many software packages still haven't implemented the HTML 5 outline logic for section elements.

