why should the <tfoot> be align between <thead> and <tbody> rather then at the bottom after the <tbody>?

<table>
    <thead>
        <tr>
          <th scope="col">Name</th>
          <th scope="col">Email</th>
          <th scope="col">Job role</th>
        </tr>
    </thead>
    <tfoot>
      <tr>
        <td colspan="3">Data is updated every 15 minutes.</td>
      </tr>
    </tfoot>
    <tbody>
        <tr>
          <th scope="row">Franklin Gomez</th>
          <td>gomezpr@gmail.com</td>
          <td>Web Designer</td>
        </tr>
        <tr>
          <th scope="row">Andrew Balck</th>
          <td>andre@example.com</td>
          <td>Front-End Developer</td>
        </tr>
        <tr>
          <th scope="row">Dave McFarland</th>
          <td>dave@example.com</td>
          <td>Front-End Developer</td>
        </tr>
        <tr>
          <th scope="row">Guild Hernandez</th>
          <td>guil@example.com</td>
          <td>Web Designer</td>
        </tr>
    </tbody>
</table>