Sounds to me more like the author has weird friends and never had a stable relationship in her life. Relationship sharing is awesome if you have a stable relationship. And people usually don't talk about their kinks in this weird fashion.
In fact, I think the Internet has increased eroticism manyfold. Look at porn apps, games and websites. People are more open about their sexuality than ever, but anonymously.
Can you elaborate more about relationship sharing? Do you mean having an open relationship or something else?