I think when something is pervasive but hidden, there's an urgent need as members of a social species to find out and become part of it. When it's discussed so openly, there's no fear of being out of the loop, just a decision of whether you think it's worth pursuing or not.

There was a sexual comedy that came out some years ago that said the openness of sex led to an increase in social acceptance of more things out the norm. The main characters however complain that they missed out because they grew up in the 80s when HIV hit which led to a massive backlash and obvious public health scare. The characters are all friends and they eventually plan a party based on what they think they missed out on. The theory makes a little more sense to me.

The 70s were also the last decade before HIV/AIDS, I always thought that had a big impact.