'70s sexploitation "Score"

I recently watched the '70s sexploitation flick “Score”, and was impressed by a certain scene. There are two couples in the movie, and at one point they split up girl/girl (pretty standard in any flick of the genre) guy/guy (whoa, cool).
What I would appreciate some input on, especially from those of you that remember the sexual revolution, is how common this would have been in the early seventies. I mean after all it was the Ziggy Stardust era.
If this wasn’t too unusual, at what point did sex flicks become so regimented- Anyone who subscribes to Cinemax knows what I’m talking about.
I’m wondering what the reaction at the time would have been and it’s hard to find that kind of info.