What I'm saying is that conquest obviously requires total military activity, and it seems like domination works basically the same way. The only difference is whether you take vassals or you're just a genocidal maniac.
I guess I'm asking if domination victories can be achieved by something other than military might.
In smaller worlds or in Archipelago-like worlds (especially with few civs), the other way to achieve Domination is by monstrous REXing with the aid of a big tech lead. Try the following:
Archipelago, medium-sized map, high sealevel, rocky, Darius (Victoria also works) of the Portuguese, epic speed, no barbs, no tech trading, no vassals.
When playing this, make sure to focus on city building (preferably with more spaced cities), commerce & teching. Make sure to have a really strong infrastructure to survive crashing after REXing waves, beeline Code of Laws & Optics, spam settlers, some garrison & carracks, then beeline Astronomy & Economics (Liberalism helps a lot here). Afterwards, go for Communism (State Property = more production & no distance manteinance penalty). Using Privateers to kill rival galleons will help a lot. Don't open borders & block off coast.
With all that in place, you just need to spam settlers, a bit of garrison & ocean-going transports (don't forget the workers, for some commerce & food land improvements). THEN it's just a matter to settle all the land you can get, develop your empire's population & get a Domination victory.
Maybe we should make a Role-Play challenge out of this...