To clarify, I'm not making any distinction between gender and it's not okay for anyone (I'm someone who has witnessed much more woman -> man harassment than man -> woman). I'm also not the person making these rules, I just try to obey them. Sexual harassment can be strict given the outrage of cancel culture and the like. I think it's better to err on the side of caution, unless you don't care about your job and like to live life on the edge.
I've known people in relationships who work together and from my experience it hasn't caused issues but it can also be considered sexual harassment. One of my past jobs was clear that you could not have a relationship with someone on the same team and especially not with someone in a superior position (since that could be seen as special treatment).
I also wouldn't really compare high school with work life since high school is a time when people start finding relationships and classmates are close with each other. It's not the same when you're getting paid to do work. Not to mention, you're supposed to be a responsible adult at this point so I would say there is more responsibility to not being seen as a creep and making an uncomfortable environment for others.
I also wouldn't say that this is saying that people need to be machined. I disagree with that completely. But there are rules. When your actions actually affect other people, that does matter. I'm all about having fun at work and I've had some really great times talking about podcasts, playing VR games, having office parties, playing with puppies, etc. There is a difference between good fun and potentially harmful or discomforting actions.
There is a line between censorship and freedom of speech and to be clear I am completely anti-censorship of any sort. But freedom of speech doesn't protect you against inciting violence against other people.
And, um, if you are in a relationship with someone at work... please don't try and do "stuff" at work.
ffs, just do work. lol