Erasing 99.9% of any population from a continent is bad (unless you meant Aztecs, specifically).
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I think to this day, a majority of people think 'less advanced' = worse
And in terms of comfort, sure. That's accurate. But our comfortable, advanced lifestyles aren't sustainable without major changes. We're quick to innovate and slow to mitigate.
Personally, I value tribal peoples simply due to the fact that while we can damn rivers and clear-cut forests, we don't have to. We can live in harmony with nature (not to sound like a hippy or whatever).