I'm new to deity but i cannot make it till renaissance or later unless i intentionally attack aggressive warmonger when i feel they are going to erase someone even if the war i'll wage won't get me a city or additional land.
It spreads their armies thin enough for the squishier civ to be able to defend it self and not let the early warminger run away.
In my experience your observation is correct unless the human player intervenes, however on the other continent there is always a player or two that are erased early if there is an authority warmonger on it.