If you want to hide some truth about yourself, it's because you indirectly try to control how I act with you. Limiting knowledge is like putting blinders. You do that because you're trying to make me go where you want. You are afraid I will act in a certain way if I know some particular facts about you, so in order to make sure I don't act that way you put those blinders on me. I call that a form of manipulation. You may use another word, but it won't change what it is.
Are you justified to use this form of manipulation? Considering everyone does it, I'm tempted to say yes. In a world where everyone cheats, not cheating would be foolish. But it doesn't change it's a form of manipulation.
As for what information I can get about you, I'm certainly entitled to do whatever I can to get any information, provided whatever I do is legal. I have control over what I do and you have nothing to say about it. Can I force you to disclose information about yourself? Of course not. Can I search your past and talk to people who know you in order to learn whatever I can? Of course I can. Don't like it - bite me.
That's the world I live in. Is it the real world? I believe so.
Now my point for all this is I dream of a world where no one could lie and pretend to be better than they really are. I dream of a world where people would be judged for who they are instead of being judge by how well then can lie and manipulate. Do you think that world would be bad?