That was a mistake on their part. They made this shell of their ancestor survive by planting its clones for it. Maybe it was because they are actually slaves to their parents that they felt compelled to protect her body. It could also be because of the ignorance of a young race and their love for their ancestors.
Mother High Heaven didn't interfere because of the rules that bound her. She could have ended it all before it started, but she didn't. She also didn't help the ancestor in her quest to resurrect. Besides, she thought there was nothing to worry about. The high elves were simply incapable of bringing their ancestor back to life. They couldn't even sense her existence.
That changed when Monarch High Heaven appeared. He sensed the dead spirit of his ancestor living within the old, decayed spiritual connection between high elves and spoke with it. They made a deal, and he fulfilled his part of the deal by protecting the clones of the spirit in the world of manifestation.
