Building projects require measurement and blueprints, even if they are just a sketch. Especially when a high degree of precision is expected or observed. Dave don't you know that?<quoted text>
"The culture in question seems to have dissolved rather abruptly some time around 1000 AD and researchers are still seeking answers as to why."
Why would they have to have writing?
Interchangeable parts are pretty hard to manufacture without precise communication skills in abstract. With the Greeks we know their math and language. With ancient South America we know so little about their methodology and semantics.