Do you believe that people that use a Post Office Box number are hiding from something or somebody?

A lot of people use post office box numbers to receive their mail. I have never understood why. It seems to cast a shadow over the box owner, as if they were hiding something. Post office box numbers and their owners, are well-guarded by The U.S. Postal Service. Question: what are some of the reasons a person would receive their mail at a post office box number, rather than to receive their mail at their home?