I think it's simply that the generation for whom the sex was a "forbidden fruit", has become old, the one after them, had enormous amount of sex just because they now could, and for the subsequent ones, sex is nothing special. It is too easy to get - guys who are now 70 year old, had to "win" girls when they were 20, now 20-year old girls are just sitting on Tinder waiting to hook up. It is as uncool as buying canned tuna vs going fishing. If anyone can do it and it's nothing to be proud about, what's the point?