- If you claim that the assistance of alien visitors is needed to explain the milestone leaps or technological achievements of ancient human civilizations...are you walking into a https://en.wikipedia.org/wiki/Turtles_all_the_way_down logic trap? Because obviously "our" alien visitors would have need even greater leaps and achievements in their own past, to be able to travel to the earth. And their visitors similar, and so on.
- Based on the folk & religious beliefs of a great many cultures, it's easy to argue that human societies have a very strong bias toward believing in anthropomorphic supernatural beings - be they angels, demons, ghosts, spirits, or whatever. Are von Däniken's ancient aliens anything more than "random" meme, which turned out to be an excellent fit for the social environment it found itself in?