Given the nature of the more spoilery aspects of goblinkind, I don't think it's really apt or fair to compare them to real life societies.
Goblins are minor demons created when a major demon escapes from hell. They aren't a natural race, they are literally fragments of evil specifically designed to carry out the ill will of the escaping demon. For all we know, the demon may rule by magic means of pure fear, for example, making interfering with his war plans, by infighting or other means, more terrifying than following orders. Goblins, due to their demonic nature, may be physically unable to act against the will and plans of their master.
With DF being VERY unfinished, we have no real way to gauge how goblin societies should act other than the little they do now, as in the next coming releases they may drastically change, as they have multiple times.
I'd really like to see goblin society expanded on, though, so we get a conclusion to how it actually runs. But I don't see the point of arguing about it like this, as though DF has some simulation aspects, it is still heavily a
fantasy game and deals with things which may not make any realistic sense outside of the boundries set by the game world.
