I’ve known a few people like that, and it had a darker undercurrent: they didn’t disbelieve that, say, the Greek or Roman monuments were built by those civilizations because they viewed those as predecessors of their own, but they considered the pacific or Central/South American cultures inferior and didn’t want to believe they were capable of great engineering.
Beyond the strong whiff of racism, I think there was also this idea that civilization went on a single path (grain, the wheel and domesticated horses/oxen/mules, bronze, iron, guns, steam, etc.) and so anyone which didn’t follow that path was basically developmentally challenged. This definitely did not consider the possibility that not every region had the prerequisites to follow the same path.
An interesting observation, that racism link. Fills a glaring gap in a sad part of my own family history.
My own favorite example of this is how the pyramids (and all the advanced trigonometry required) were built by the Egyptians prior to their discovery of the wheel
I've heard this claim many times, and yet I remember VD books (and similar ones like Kolosimo's) discussing Prehistoric Europe including cave art and megaliths. The Ancient Aliens TV series does have episodes on Ireland, the Norse and Graeco-Roman mythology.
Even today, these types bring up Baalbek's massive triliths on a regular basis, and state they could not have been built by such classical civilisations.