You're giving to much credence to the genealogy of ideas as a driving force for social change.We are not talking about the historic practice of arse-banditry. We are discussing the philosophical negation of common sense, moral standards and the very fabric of reality itself. Foucault and his fellow travelers tried to create a social milieu that supported their degenerate life styles by attempting to sway how people felt about the very nature of reality. They have succeed by and large, as it relates to matters of gender and how societal views related to the sexual exploitation of children are now changing.
When it comes to behaviors that might be described as 'degenerate', or maladaptive as I'd refer to them as, an increase in mutational load due to relaxed selection pressures is likely playing a decisive role.