...But, as Nog and Jake go to show in "Progress", anything can be used as currency as long as there's hope of converting it to some other currency as situation warrants. Quark couldn't exactly covet latinum on Earth, but he could collect all the gold he can get, then sell that to somebody who values gold but has dilithium to sell for it, and then convert that to GPL when reaching what he considers civilization. It's likely that many primitive civilizations accept gold, considering that it is pretty, malleable, conductive and rare. And swindling primitive civilizations must be covered in the Rules somewhere.
I'll grant Memory Alpha the benefit of doubt: their paragraph on latinum might only be claiming that the statement "For ease of transaction, latinum is usually suspended within gold to produce GPL" is derived from the episode, while the rest is intended as speculation.
I've only seen "Who Mourns" once, but I'm pretty sure nothing was inserted into the dialogue about nonreplicability. The confusion regarding the reference seems to stem from the Memory Alpha phrasing exclusively, although everybody and his cousin has been suggesting that the substance is somehow unreplicable ever since it was introduced to the Trek universe. Possible, I guess - but it would be pretty strange, considering that very complex things such as living tissue have been successfully replicated in various episodes.
Timo Saloniemi