Keep it sci-fi. Idiocracy is not innate to the human condition, it's a result of content curator algorithms and spambot ecologies crashing semantics on a species-wide scale. The outward bound are either Dunbar-number habitats or those ahuman but incisive probes. Both are at a loss as to how they should recolonise the homeworld without being dragged into its cognitive black hole. The great filter might be technological Alzheimers.