ETA: Also keep in mind that you are bringing resources back from another server that were never meant to be on your home server, thus messing with an economy that is already not so great. If you continue exploiting, the value of the ore on your own server will go down (More supply) and up on other servers (less supply.) So in the long run, you’re really only hurting your own economy. Again, this is almost certainly an exploit, and not something that was intended in the game design.
Not to burst your bubble, but your wrong. The Broker is cross server, so it doesn’t matter what server he mines from, it will be on the same broker everyone else has access to. With the free server transfers currently it wasn’t fully intended this way, but once its a fikittenl of gems to transfer, Anet will want you to server hop for nodes.