Why does criticizing an impossible assumption put the onus on me to identify economies that do not make that assumption or to envision what such a state of things might look like? Is it not sufficient to refrain from obvious error?

That wasn't criticism, just curiosity. I'd like to have such an example to refer to and thought you might have one.

Unfortunately, the exponential-growth economies ate them all.

If there are any, they're probably in ancient societies, and as such are probably poorly understood now.