Our other thread fleshes this out, but there's a difference between widespread idiom and accepted definition. A dictionary's description of idiomatic use does not indicate that the term independently denotes the idiomatic meaning.

Similarly, if I say "cats and dogs," that isn't a measure of volume or intensity except where paired with "raining." Having to say "of civilization" indicates that "cradle" is being used metaphorically or idiomatically.

Please be more charitable. None of what I've said is misinformation.