It's fanon, admittedly based on behind-the-scences production intent, that latinum is not replicable. It was never
established in the show that latinum was incapable of being replicated.
So why would we start spinning yarns about how replicators can't produce latinum, when there's no canonical evidence to support that idea? The idea that an interstellar civilization would base their economic system on the "worth" of some unreplicable materials is unimaginative. "Gold-pressed latinum" is used as a currency by the Ferengi Alliance, and that's all we know. The idea that it is worth using as a currency because it is unreplicable is similar to assuming that the US uses paper-and-ink currency because paper and ink are rare. Obviously neither paper nor ink are rare substances, nor are electrons, which are the real
currency of our times. So why would latinum, or gold-pressed latinum, have to be rare and unreplicable to be used as currency?
Answer that question, and I'll assist in figuring out why latinum and GPL must unreplicable.