Hi Kninjanin,
As you already know, I like the Q/A sites more than social media like Facebook. And I myself have learned to be a little bit careful there, although sometimes I wonder if I should be even more careful!
So I was on AnswerMug for a while, and met people I really liked...and there was one woman who would not even tell me the country she lived in! She said she was in northern Europe, but she did not want to post her country on the Internet! She had been on SodaHead and liked it there, but she got stalked while she was there! So that made her VERY careful, and I do not blame her...but it meant that we lost contact when I left AnswerMug.
Here on SOLVED, sometimes I would like to know more about some of the regulars, like Marianne and Other Tink, because I already am friends with Rooster, we have been on websites together since the old Ask.com!
But TinkerBell and Marianne, I do not even ask them about themselves because it can be so risky...so I would say it is likely that people might want to protect themselves when they hide their posts.