Board Thread:Lore/@comment-26073467-20150715054105/@comment-27718380-20150715202917

Notice how their greed got worse with age. This is just spectulation, but the effects may have gotten worse to the point where they could be controlled. Anyway, that's just speculation. Im not trying to say that Sauron could control them, but that Melkor (in theory) could, but focused his energy on men and elves because men were easy and elves the best. The same goes for Sauron. If they had tried for the dwarves, they would have found a way, like Sauron befriending the elves of Eregion and almost being able to control them.