User blog comment:LOTRMod/On the Removal of Diamonds/@comment-70.192.35.34-20141230140528/@comment-27723099-20141231141628

You can get dwarven picks and forges as loot for example from dwarven towers. No other tools should be able to produce mithril.

Also if some players prefer to mine, some prefer to farm and some prefer to fight, this allows for alliances and trading. There is not much trading in vanilla MC because every player can produce everything by himself.