Neltharion the "Earth-Warder"? Meaning?

[Sereluna-silvermoon]

@Kaadirkurem-defias-brotherhood

Oh, you mean that he was to ensure that nobody from the surface would attempt to unleash the Old Gods by digging or otherwise manipulating Azeroth’s crust?

That, and probably to prevent an event like the Cataclysm.

@Kaadirkurem-defias-brotherhood

How could they not know that the whispers of the Old Gods can drive living beings to insanity?
Or they did know, but they didn’t think it would affect the dragons?

Could be that they simply did not know of their abilities. The Old God would have reason to keep it secret.