why doesn't the DOM spec include an insertAfter method, srsly guys

dom-insert-after.php

<?php
/** Inserts a new node after a given reference node. Basically it is the complement to the DOM specification's
 * insertBefore() function.
 * @param \DOMNode $newNode The node to be inserted.
 * @param \DOMNode $referenceNode The reference node after which the new node should be inserted.
 * @return \DOMNode The node that was inserted.
 */
function insertAfter(\DOMNode $newNode, \DOMNode $referenceNode)
{
  if($referenceNode->nextSibling === null) {
      return $referenceNode->parentNode->appendChild($newNode);
  } else {
      return $referenceNode->parentNode->insertBefore($newNode, $referenceNode->nextSibling);
  }
}