Yes, the Conquest and Domination were two different victory conditions, but the Conquest condition was pointless since you'd reach the Domination condition first.The original conquest victory was to capture all cities (I still remember searching for this last city AI found on a remote island). The solution you're describing was in Civ 3 and 4 only. It was scrapped with the introduction of tall gameplay viability as incompatible. And while Civ 6 and 7 are not that focused on tall gameplay as Civ 5 (luckily), they still allow this playstyle.
Ironically, a working diplomatic system is what's needed to allow peaceful empires to compete against conquerors, but that's what Civilization has never yet had.