If Armok is omnipotent, he is infallible...
That depends on your definitional framework. One traditional view is that supreme deity-ness is comprised of three factors: omni-potence (unlimited power in strength, coverage, and range), omni-presence (unlimited viewpoint & knowledge in strength, coverage, and range), and omni-benevolence (unlimited mercy in strength, coverage, and range). Many "lesser" powerful beings of myth, legend, religion, and fiction are less than unlimited in some of these aspects; just like Superman is more interesting because of Kryptonite, these limitations usually make for more interesting stories.
In some settings, it can be postulated that an entity might be capable of creating a vast and complex world, of ultimately being able to control the destiny of things small and great within it, but not having perfect information on what is going on; and not necessarily either willing or able to interfere in certain situations.
Consider the player of DF *from the standpoint of the dwarves in the simulation*... you created their world, and using both built-in and memory hacking tools can make drastic changes. You can smite or resurrect dwarves, change their thoughts and genders, give them super-powers or horrible curses... yet how often do you actually bother to do so? You have the *power* to do almost anything, but usually only wield it in furtherance of your own goals, or when some individual catches your fancy due to heroic or eccentric behavior. You can also end up distracted by events elsewhere; many posts on the forums mention dwarves found starving or dead because their overseer was distracted or preoccupied.
Consider: truly omnipotent power would be so far above the level needed to create a universe that it requires tricky math to even compare one to the other. Let's represent the power to create, populate, and minimally oversee a universe as 1. A being of unlimited power should be able to create an infinite number of such universes, right? So that's a power of ∞. But shouldn't they be capable of creating *another* being, lesser than themselves, who nevertheless can create universes? Why not an infinite number of such beings, creating an infinite number of universes each? What if these beings could themselves create still lesser beings, but still capable of creating infinite universes... and infinite-universe-creating-lesser-beings? Why not have an infinite hierarchy of such beings? Why not create an infinite number of beings who can each create an infinite number of such infinite hierarchies? All this is *still* less powerful than "omnipotent".
When most people talk about "unlimited" power, it's sadly pretty limited. Someone with a better knowledge of cardinality can probably construct a sequence of unlimited power that dwarfs (pun intended) the above cascade; I will point out that Toady One has a PhD in mathematics from Stanford. (Math is a vengeful god, and his name is Armok?