It is p much a certainly that conworlding is always being done wrong, mainly because our silly simulations generally cannot hope to capture the full complexity of whatever system we are making up. The fact that you cannot possibly know enough about ALL THE SCIENCES feeds this, of course.

(nb I hold that this is also true for conworlds that run on fairy dust of some kind)

However I am equally pretty sure that this idea is not new (in fact I thought of it myself, and I am not some kind of super economopolitical genius so it is very probable that at least a few other people thought of it long before me), but a) rarely implemented because it is more annoying to work with than slowly doing one culture at a time and b) probably not something the grand majority of conartists must be assumed to have thought of.