It seems like this parallels the need for encryption. I don't over-share in meatspace for the same reason that I don't deliberately make myself vulnerable in cyber-space.
I agree, but, I also wonder if some of this 'it is okay to share' is because of social media's influence on what is acceptable to disclose.
No, it's just immature thinking from people who aren't familiar with the workplace and its norms. If it wasn't social media it would be some IRL friends.