Well, the whole ascension thing was another dodge. They had to posit that "rules" prevented the ascended Ancients from doing anything. The Asgard were usually sidelined with the replicator threat for similar reasons. The reason of course is that if you allow real help from such a powerful, virtually omnipotent ally, the episode and the series would end right there with "... and they all lived happily ever after."
You want powerful allies, or powerful forces out there in the universe, but you also don't want them to fix everything with a wave of their hand. But searching
for such beings, or their weapons, made a great plot device and provided a stream of MacGuffins.