I think the point where it happened was when we, collectively, noticed that people were exploiting professional power asymmetry for their own sexual gain. Often at the cost of another human's dignity and self-respect – not to mention career prospects.
However, the difference is that in those cases, it is always the woman's choice to participate in it. Since they are the marginalized demographic in this matter, the choice should be theirs to indicate what is and isn't acceptable commentary, discussion or behavior in the workplace.
Today's environment is one where it’s _men_ who overwhelmingly decide, by way of majority-reinforcement, what other people should consider to be acceptable or not.
It all comes down to marginalization: we don't marginalize or trivialize people—or their accomplishments—based on the fact that they eat. However, our society does tend to do those things to people based on their gender; specifically, to women based on their gender.
Once we eradicate the culture in which that happens, people can express themselves sexually more freely and without hesitation, in the safe and sound knowledge that doing so won't instantly label them in a certain way that would dramatically (in a negative way) impact their professional and/or social lives—or worse.
More here: http://www.amazon.com/Civilizing-Process-Sociogenetic-Psycho...
Eating doesn't affect anyone around you (though tuna sandwiches are definitely an issue to get HR involved in...) Sexuality, violence, religious conversion and the stench/filth of defecation affect people around you whether they want to deal with them or not. Ergo, it is rude to make "working" contingent on dealing with your literal or metaphorical shit.
At what point did we become okay with excluding sexuality from human lives, or a large portion of them -- the time we spend working? Sexuality is every bit as much a "human" endeavor as, say, eating -- and we don't (currently) say: never eat at work, work is for work only (despite the fact that food does separate people from each other, and accentuates differences).
Anyway, a random rambling, but I thought I'd share anyway...