'Progress' is largely responsible for causing mass extinctions, but de-growth is ridiculed by most. Further manipulation and exploitation of the world (terraforming, electric vehicles etc.) is widely seen as a more sensible solution to environmental collapse than a humble stepping down (or climbing back up? From the depths of hell?), back to less resource-sapping ways of living.
Primitivism doesn't have to mean digging for turnips in the mud while your teeth fall out, or geodesic domes and yummy mummy farmers' markets. Despite the toll it has taken on the Earth, 12,000 years of agrilogistic civilisations has produced some very useful tools and thoughts. If a society became primitivist there is no reason (and probably no way?) this would all be forgotten. The possibility of being able to choose what to remember, what to forget, and what to explore and develop further makes primitivism very attractive - but also dangerous.
From this junction point I will paint a picture of an idealised cultural, philosophical, and technological model.