It is a self perpetuating cycle. On 4chan the idea a nieve gi is prozed because you don't have to otherwise socially sucessful to impress one. Which is about as a high a bar as a NEET could imagine passing so that is reinforced.
Howver for conservative society in general they demonize sex. So then a sexless woman, a girl to young to be sexualized, is the ideal partner.
You get weird religous hyper fixations, and material historical forces playing in there creating weird combinations and you have whar we get.
Monogamy being financially advantageous is just one externality of patriarchal resource allocation.