In one sense, I do think Empire: Total War (or perhaps HOI 3?) would be a better choice for domination-VC-only players than CIv 6. Still, even Total War veterans complained about the AI system too.
Otherwise, Civ 6 MP games among domination-VC-only players might be another alternative. I could imagine these players would agree with each other that things like CB, warmonger penalty, loyalty, Golden\Dark ages, emergency, governor and so on are stupid game designs, and are not essential for their competitive gaming experience. Even the districts system as a whole could simply be another 'micromanagement' diverted from the core of their gaming experience. Another stupid thing in short.
And I would be of interests to watch such game. How do the human players believing that you do not need to build anything other than military units (since other Civs would build for you) play with each other, in the context without any AI civ to exploit? That's a good fighting worthy of being watched I suppose.
After all, I would agree with the CIv 6 in-game text: the domination VC is the easiest one to get in the Civ game. For the single player Civ game this might indeed be the case.