This is just an extension of one's privacy. People will keep their privacy - even from friends - for any number of reasons. I think it's rarely a case of doing other people harm, but more often out of a desire to protect themselves (including any information about themselves).

I totally agree with Peachey!

they are afraid of being exposed i suppose:) some people are weird in this place.:)

As far as I know, these people has the untold secret. It happened to me that these people using the deframe language on my blackboard and they keep their blackboard in private in order to prevent some one will do the same on them. Some of these people also in consipiracy to control the outcome of the answers, making the correct answer incorrect answer and the incorrect answer the correct answer. I complainted to italki, these people that I complainted were found something in common, they all keep the message and blackboard private. One exception, Jura, she kept the message and blackboard private for some other reasons.

my board is open to any one..i can't give any good idea about this question... cowboy...