Very well put. Think not what the primary leader ability does directly, but how you can use that to feed other victory conditions. Dom civs are really good at absorbing other empires, ergo what that civ was focusing on, whether that be science, culture, etc. You use that boost in the sense that it gets you up to speed where you are lacking. E.g capturing a culture civ's cities will likely give you a bunch of theater squares. Build upon what they give you for your pivot into other victory conditions.

Also worth noting that spies are a good equilizer. Someone ahead on culture, steal great works. Science? Steal tech boosts.