From what I've read, and there are a number of books and articles on this period in the business, when they weren't fucking for the camera they were fucking anyway and, yes, drugs were a big part of the scene (there are a few rare scenes that include cocaine use, though hard to find. It was a rather open and free environment and most anyone was welcome to join in. Then came AIDS.
I think they just go with the flow. The slow sex looks like they all smoked weed or did drugs. That is so 1970s! Natural tits, nice bushy pussies and a lot of sex. I like that. They also do not use condoms and cum on tits or belly.