I agree on Jeremy's last post being a good one.
Clint - let me give an example that specifically relates to me and how this affects me.
In my profession money is king. Most everyone who is rising in my business probably wants a 10,000 sf mansion and a fleet of Mercedes in the 10 car garage. I am interested in backpacking, spending time outdoors, the tiny house and minimalist movements interest me. In my profession that might be considered odd/contradictory. I don't want to quit my job, I'm not lying to anyone telling them that I want a mansion with a helipad, they can think what they want. I am a young, aggressive, sharp guy that wants to rise in my field, make money, be the boss eventually or own my own company. That's all they need to know about me. So for me, something as innocent as posting about the tiny house movement might be a red flag. 'What is this guy some kind of liberal hippy? backpacking?, camping under a tarp on the ground? Tiny houses?'
This is just one example.
One of the main reasons is I just don't want to make vast amounts of information about myself available to anyone that can run a search in google. Just from a privacy standpoint, it's none of anyone's business. The only person that needs to know everything and everything about me is my wife (and she does).