So while the dwarves morn, any orc passing by would celebrate the rise of the power of Moria for the shadow. However, it was now a power of the followers of Melkor. Take Moria the tremendous dwarven city was lost to the orcs. As well as the physical removal of the Valar from the world as Eru remade Middle-earth.Д¬onsider, however, that Tolkien at various times mentions losses of power, but these can also be gains of overall power. Other examples include the binding of Morgoth, the fall of the Numonrians at the hands of Eru, and later the decay of the northern kingdom of Arnor. The elves are the closest to Eru Iluvatar, and their leaving Middle-earth is in every way a reduction of strength to Middle-earth in the last ages. Further, the elves were leaving Middle-earth and returning into the west across the seas as their numbers continued to dwindle. The Noldor elves were significantly reduced from their wars with Morgoth in the first age and later after the battle of the Last Alliance. However, in the case of the Elves, they had been reduced in military might. But I think we need to be careful when Tolkien mentions the Eldar days' superiority as he can often refer to cultural superiority rather than military superiority. I don't have stats handy but I think Tolkien portrayed an overall decay from the Eldar days to the third age.

Battles of the third age