Originally posted by Grailoch:

Duh! Do you really need to ask? Of course it is cheese. Why would you question it?

The reason I would question it is that developers implemented a mechanic to prevent players from transporting ore through portals.

Why are characters allowed to travel to different world with not only all of their equipment intact but also the entire content of their inventory? So developers knew that players could use this mechanic to cart large quantities of ore but chose not to implement a game mechanic linking ore to a specific world.

So it's not entirely clear. Linking ore to a specific instance of a world would probably not require a lot of code. So why have developers left that grey area in the game?