>They didnt do connectors or mortar, let alone concrete.

I personally chalk that sort of stuff up to living where the climate is set to easy mode.

Compare construction that predates building code in wealthy coastal California to poor rural Maine and you'll find the latter is routinely within spitting distance of compliant with modern code because that's just what you need if you want your project to resist nature for a "worth the effort of building it" amount of time.