Why should you tell an officer something that you're not legally required to? It's none of their business, and if they can look it up, they can go ahead. It's a means of peaceful resistance to a procedure that's arguably unconstitutional (fourth amendment).
Personally, I usually travel with family, so I don't want to make a scene. But when I travel alone, I'm a bit more resistant to trade my rights for convenience.
I completely understand and respect people who peacefully resist border security, and hopefully those agents learn a thing or two about where the limits to their authority are. Please don't be a jerk about it, but you should never be compelled to give any more information or assistant than legally required.