On the wiki, it is mentioned that the Greybeards consider the very existence of the Elder Scrolls to be a blasphemy.
Why is this?
According to the wikipedia article The Elder Scrolls are by nature unstable:
The actual number and placement of elder scrolls fluctuates constantly as it is said that they technically exist and do not exist at the same time. This makes their predictions difficult to cite authoritatively because entire scrolls or entries can change or vanish as events transpire. This unpredictability has caused other ascetic groups, such as the Greybeards from Skyrim, to find the existence of the Elder Scrolls a blasphemy.