The circumstances required for the production of Cosmic Erosion Elixir were extremely stringent, even on a universal scale. In fact, even if many Minor realms or realms were destroyed, they might not produce this elixir.
The first most important requirement was that the realm needed to be extremely stable, and should otherwise appear completely inline with its normal lifecycle. The stability of the realm meant that the space it constituted would be extremely stable, and capable of healing normally and naturally should anything happen.
The second requirement was a significant and constant destabilizing factor. This factor should be strong enough to strain the laws of the realm constantly, but not strong enough to actually unravel the functionality of the realm or its laws.
The third requirement was that the realm should not be fully mature, and should still be in the growing phase of its lifecycle.