No idea, but whoever agreed to start spelling Tiahuanacu with a W deserves a quick punch in the shorts. It’s a Spanish name for a place whose original name is lost to time. I don’t care if the present-day Aymara speakers spell it with a W. That’s a modern bastardization of the Spanish name, not an authentic reproduction of the original. Just because the Aymara speakers were ignorant of Spanish spelling conventions doesn’t mean we should all copy their mistake.
I don’t think there is enough information to conclude they abandoned metal tools. The Wiki article says the society collapsed and disappeared around 1000 AD. There is very little left to make accurate inferences about the society let alone that they abandoned metal work. The society suffered a drought, loss of crops and massive starvation and completely collapsed. Any traces were wiped out by the Incas and the Spanish. They didn’t abandon metal work, that society simply ceased to be along with all its knowledge.
New Scientist recently published an article on the myth of technological progress - there are plenty of really clear historical examples of innovations being abandoned and lost. One example was the chinese Admiral Zheng He - his fleet was massive, with huge ocean-going vessels, and he explored the Indian Ocean coasts in seven expeditions. At the end of the last one, the fleet was dismantled and China did not recover these skills.
The reasons for these collapses are not always clear, but in some cases it is the collapse of a caste or dynasty, or maybe just a lack of use - the US military almost lost the ability to make FogBank (a component of themonuclear bombs) because although the process was documented, the facilities had been decommissioned, the specifications were incomplete (the original source material had a low-level essential contaminant no-one knew about), and the original scientists had retired or died.
So a culture abandoning metallurgy is not surprising.
Si
Hell, in my own lifetime, the US has gone from having a very aggressive space exploration program to cutting back so far that we’ve just about abandoned space technology.