I'm doubtful. Which small communities that did this are you referring to? And is the thing that made them successful something that's just hard, or is it something innate to their being very small?

If it's the latter, I don't think that checks out; I interpreted "we know how to build societies that don't do this" as "we know how to build large-scale human systems that avoid these trends; systems that could exist at scale on earth today".

Otherwise the claim just ends up being "we know how to do this if we start tabula rasa" (fun thought experiment, can't happen) or "we know how to do this if we get rid of 99.9% of the population and go back to village-scale economies" (not worth it, and the process of getting there would be exploited).