I dunno about this. Attributes are supposed to be metadata, not displayed textual content. Like it's fine to give the anchor for a section as an attr:

    <section id="animals">
      <h2>Animals</h2>
      <p>Here are my animal facts</p>
    </section>

I would feel strange if a browser's built in CSS were reaching into an element's attribute and rendering the text therein as something visible to the reader.