If we had always followed the "don't say it" default, then it would still be considered offensive to advocate for LGBT or religious or gender rights in the workplace. This is what I meant by taboos being sometimes harmful.
Everything I've seen in all the jobs I've worked shows a massive disconnect between "HR reality" and actual reality. I've seen women openly and proudly objectifying male subordinates in company meetings. I've seen men spending extensive time distracting their female coworkers with no consequences. I've seen women objectifying the "hot catering delivery boy". I've seen salesjerks harassing and flirting and getting away with it, while genuine people are slapped down for trivialities. The loudest and most prolific swearing I've ever heard was in a company with a highly religiously conservative employee demographic.
Nowhere have I seen a workplace where people robotically clock in, work silently, and clock out. Never have I seen a workplace free of non-work-related conversations.
People spend a majority of their waking time at work or on work-related matters. A sizable proportion of couples report meeting each other at work. There's simply no such thing as a work-only workplace. The HR-ification of society only facilitates the kind of abuse and discrimination that the devious get away with and the genuine get blamed for.
Again, you're equating social progress with the ability to say controversial things at work. I would argue that most of the progress LGBT/religious/etc. groups have made have been made outside of office cubicles. More importantly, there's a clear difference between "what are we doing to encourage a more diverse group of developers" to "who do you think is the hottest engineer on our team?"
I'm still failing to see what your point is. Yes, some people can choose to violate the rules and risk getting away with it or not.
You're probably better off asking your HR for a training if you can't fathom what topics may be appropriate for work or not. But most of it is common sense.
Is it sexual/racial or otherwise offensive to some within earshot? Don't say it.
Is it possibly offensive but you're not sure if they'd like to hear it? Don't say it.
You're there to work, not to push societal boundaries/ maximize discourse.