I am skeptical of this assertion. If you walk the mountains of Nevada along the fossil shoreline where the Lahontan[0] civilization thrived, you will regularly

I am skeptical of this assertion. If you walk the mountains of Nevada along the fossil shoreline where the Lahontan[0] civilization thrived, you will regularly find large quantities of neolithic trash strewn about. Broken, half-finished, or abandoned stone tools are ubiquitous. It takes little effort to find obsidian arrowheads, some in perfect condition. The preponderance of the evidence is that these were viewed as disposable artifacts, use once and throw away. If they were actually valuable, they could have picked these up in the same way we pick them up today. It would have essentially been "free money" lying on the ground. Yet for some reason, in all the intervening millennia, so few people did that modern humans can find them everywhere. [0] https://en.wikipedia.org/wiki/Lake_Lahontan https://en.wikipedia.org/wiki/Lake_Lahontan