First off, there’s the commercial factor. It’s expensive to release movies in theaters, and I don’t mean because of production budgets: Anything opening wide requires a low-to-mid-eight-figure ad buy, at least, more if you really want to pop on that opening weekend. The increased cost of advertising means fewer films get released in general, and those few need to be home runs, not singles. And it’s harder to hit a home run with an R-rated movie than a PG-13-rated movie.

(Congrats: You’re caught up on the last 30 years or so of the theatrical exhibition business.)

A PG-13 movie isn’t just easier to sell in America; it’s also easier to sell overseas—particularly in China, where films forbid all sorts of things. Ghosts, weirdly. Depictions of homosexuality. And nudity is a no-go too. So, if you want to try and recoup any of your investment in the Middle Kingdom, better make sure you’re not going to have too many nude scenes to cut out.

Indeed, discomfort with sex lines up nicely with the rise of the comic book movie and the sexless action flick. Writing all the way back in 1976—practically a hedonistic paradise compared with now—Pauline Kael highlighted the rise of the cop movie and the ways in which police partnerships subbed in for real romantic relationships. “It doesn’t have the hidden traps of the relationship between man and women, or between lovers of the same sex,” Kael wrote in “Notes on Evolving Heroes, Morals, Audiences.” “Two human beings who are sexually and emotionally involved cause pain to each other, and it takes more skill than most writers and directors have to deal with that pain.”