Does it take a thinking man to write ? or does writing itself help you think ?
A little bit of both I think. I can't recall the number of times when, faced with a specially knotty problem, I started to see the light after writing down the problem and reading it back to myself.
Paper and pencil are good for this but they don't let you erase and fix things quickly as your thoughts evolve. Computers make changes easier, but the interface is still so awkward for freewheeling ideas that they are hopeless in capturing a half-formed thought.
Whiteboards are the perfect medium. They are large, giving you lots of space to express yourself, you can erase quickly and conveniently, and they offer the same elegant input interface as pencil and paper.
Some ideas are too simple and elegant to improve on - and the whiteboard might well be one of them.