Non-Existence

"Why do you think the creator locked the elder horrors behind the gates?" Nyx asked as she seductively sipped from a glass of red wine. 

"Because they are uncontrollable." Abaddon answered instantly.

"They are the true manifestations of that which is incomprehensible and malevolent. But what does that have to do with nonexistence?"

Nyx swirled the wine within her glass as she tried to figure out the best and most efficient way to explain the connection. 

"Put simply... that is the source of their power. Or the root of their makeup.. I'm.. not really sure which. 

Think of the world and how mortals and lesser gods exist three dimensionally. Yet primordials and powerful gods permeate all four.

But the eldritch things exist in realms that are only theoretical and difficult to explain for anyone other than them.